A report on a new software that enables eyes to do the typing appears in Wednesday's edition of the journal Nature. Replacing a keyboard or mouse, eye-scanning-cameras mounted on computers have become necessary tools for people without limbs or those affected with paralysis. The camera tracks the movement of the eye, allowing users to "type" on a virtual keyboard as they look at the screen. And now, researchers from the Cavendish Laboratory at prefix = st1 /CambridgeUniversitysay they have developed software that replaces the standard QWERTY keyboard layout with one that is nearly twice as efficient, more accurate and easier on the eyes. Called Dasher, the prototype program looks into the natural gaze of the eye and makes predictable words and phrases simpler to write. Any off-the-shelf camera capable of scanning eye movement can be used with Dasher, though the person must sit fairly still during the interaction.   The letters of the alphabet appear in a single column on the right of the screen, with an underline symbol to represent a space. Each letter is framed by a color1ed box. As the user looks at a particular letter on the right side of the screen and drags it to the left with their eye, another sub-alphabet column begins to emerge inside the box on the right-hand side, along with more letters framed in color1ed boxes. Dasher is designed to anticipate which letter will be needed, so although the successive sub-alphabet columns are initially very small, the letters or combination of letters that appear are most likely to be used next in that sequence. For example, if a person starts with the letter "h", the language models in Dasher will bring up "a" "e" "i" "o" and "u" in the sub-alphabet box, along with a few other possible combinations like "ello" to form the word "hello". Each box has a complete alphabet within it, though the first letters to appear have the highest probability of usage. The letters are then placed together to form a sentence on the left side of the screen.   Researchers say people will be able to write up to 25 words per minute with Dasher compared to on-screen keyboards, which they say average about 15 words per minute. With a bit of practice, MacKay said, Dasher offers an easier and more satisfying way for disabled people to communicate, providing them with better tools to write e-mail or create word processor files. Mackay said Dasher could work in most languages. With the new software Dasher, people can type with their eyes through  _  .
a computer screen with eye-scanning sensors an eye-scanning camera on computer a color1ed box attached to the computer a regular keyboard with sensors
Question: A report on a new software that enables eyes to do the typing appears in Wednesday's edition of the journal Nature. Replacing a keyboard or mouse, eye-scanning-cameras mounted on computers have become necessary tools for people without limbs or those affected with paralysis. The camera tracks the movement of the eye, allowing users to "type" on a virtual keyboard as they look at the screen. And now, researchers from the Cavendish Laboratory at prefix = st1 /CambridgeUniversitysay they have developed software that replaces the standard QWERTY keyboard layout with one that is nearly twice as efficient, more accurate and easier on the eyes. Called Dasher, the prototype program looks into the natural gaze of the eye and makes predictable words and phrases simpler to write. Any off-the-shelf camera capable of scanning eye movement can be used with Dasher, though the person must sit fairly still during the interaction.   The letters of the alphabet appear in a single column on the right of the screen, with an underline symbol to represent a space. Each letter is framed by a color1ed box. As the user looks at a particular letter on the right side of the screen and drags it to the left with their eye, another sub-alphabet column begins to emerge inside the box on the right-hand side, along with more letters framed in color1ed boxes. Dasher is designed to anticipate which letter will be needed, so although the successive sub-alphabet columns are initially very small, the letters or combination of letters that appear are most likely to be used next in that sequence. For example, if a person starts with the letter "h", the language models in Dasher will bring up "a" "e" "i" "o" and "u" in the sub-alphabet box, along with a few other possible combinations like "ello" to form the word "hello". Each box has a complete alphabet within it, though the first letters to appear have the highest probability of usage. The letters are then placed together to form a sentence on the left side of the screen.   Researchers say people will be able to write up to 25 words per minute with Dasher compared to on-screen keyboards, which they say average about 15 words per minute. With a bit of practice, MacKay said, Dasher offers an easier and more satisfying way for disabled people to communicate, providing them with better tools to write e-mail or create word processor files. Mackay said Dasher could work in most languages. With the new software Dasher, people can type with their eyes through  _  .
A. a computer screen with eye-scanning sensors
B. an eye-scanning camera on computer
C. a color1ed box attached to the computer
D. a regular keyboard with sensors
Answer: