You may have never heard of Lanthanum, Cerium or Neodymium, but these elements   and others known as "rare earth" play a major role in modern technology. They can actually be found in many places on the earth, but not in quantities that can be mined. Only a few countries -- China, America, India, Australia, Brazil and Malaysia have any that can be mined enough to be traded. Even though some of these elements such as Cerium are as abundant as Copper, they are not found in concentrated amounts on the earth's surface. They are often mixed together with other metals, which makes extraction   of these elements an expensive and an environmentally messy process. It was due to this reason that the term "rare earth" was invented. Rare earth metals are used widely in our life. Rechargeable car batteries, computers, iPhones, DVD players, computer monitors, televisions, lighting, lasers, glass polishing, and superconductors all use quantities of rare earth metals. Also, with the advancement in "green" technology like solar panels, these shiny materials are becoming more important than ever. An average electric car uses 10 pounds of Lanthanum for its rechargeable battery! America has large deposits   of rare earths and has one of the first mines. It was opened in Southern California in 1940. The element "Europium" was the first metal to be separated in quantity for use in color televisions. However, in the 1980's and 1990's, as China started producing these elements in Inner Mongolia, the mines in America and elsewhere could not keep pace. The mine in Mountain Pass, California also failed environmental regulations and shut down in 2002. Now, recognizing the importance of having more than one supplier of this important resource, other rare earth owning countries like India and Australia are either dusting off their rare earth mines or speeding up their production. It is believed that the debate over rare earths will become louder in the coming months and years. It can be inferred from the text that rare earths   _  .
are now in great demand can now be used in few fields are harmful to the environment will soon be replaced by other metals
Question: You may have never heard of Lanthanum, Cerium or Neodymium, but these elements   and others known as "rare earth" play a major role in modern technology. They can actually be found in many places on the earth, but not in quantities that can be mined. Only a few countries -- China, America, India, Australia, Brazil and Malaysia have any that can be mined enough to be traded. Even though some of these elements such as Cerium are as abundant as Copper, they are not found in concentrated amounts on the earth's surface. They are often mixed together with other metals, which makes extraction   of these elements an expensive and an environmentally messy process. It was due to this reason that the term "rare earth" was invented. Rare earth metals are used widely in our life. Rechargeable car batteries, computers, iPhones, DVD players, computer monitors, televisions, lighting, lasers, glass polishing, and superconductors all use quantities of rare earth metals. Also, with the advancement in "green" technology like solar panels, these shiny materials are becoming more important than ever. An average electric car uses 10 pounds of Lanthanum for its rechargeable battery! America has large deposits   of rare earths and has one of the first mines. It was opened in Southern California in 1940. The element "Europium" was the first metal to be separated in quantity for use in color televisions. However, in the 1980's and 1990's, as China started producing these elements in Inner Mongolia, the mines in America and elsewhere could not keep pace. The mine in Mountain Pass, California also failed environmental regulations and shut down in 2002. Now, recognizing the importance of having more than one supplier of this important resource, other rare earth owning countries like India and Australia are either dusting off their rare earth mines or speeding up their production. It is believed that the debate over rare earths will become louder in the coming months and years. It can be inferred from the text that rare earths   _  .
A. are now in great demand
B. can now be used in few fields
C. are harmful to the environment
D. will soon be replaced by other metals
Answer: