The miracle bridge      The Brooklyn Bridge that crosses the river between Manhattan and Brooklyn is simply an engineering miracle. In 1883, a creative engineer, John Roebling, was inspired by an idea for this spectacular   bridge project. However, bridge-building experts told him to forget it. It just was not possible. Roebling convinced (persuade sb. to do sth. ) his son, Washington, an up-and-coming engineer, that the bridge could be built. The two of them formed an idea of how it could be finished successfully and how to overcome the difficulties. Somehow, they persuaded bankers to provide money for the project. Then, with great excitement and energy, they hired their crew and began to build their dream bridge. The project was only a few months _ when a tragic on-site accident killed John Roebling and severely injured his son. Washington was severely brain-damaged, unable to talk or walk. Everyone thought the project would have to be thrown away, since the Roeblings were the only ones who understood how the bridge could be built. Though Washington Roebling was unable to move or talk, his mind was as sharp as ever. One day as he lay in his hospital bed, an idea flashed in his mind as to how to develop a communication code. All he could move was one finger, so he touched the arm of his wife with that finger. He tapped out the code to communicate to her what she was to tell the engineers who continued building the bridge. For 13 years, Washington tapped out his instructions with one finger until the spectacular Brooklyn Bridge was finally completed. This article mainly tells us   _  .
to try your best to save ourselves in an accident never to do dangerous things to study hard the advanced science and technique to fight as long as one has breath
Question: The miracle bridge      The Brooklyn Bridge that crosses the river between Manhattan and Brooklyn is simply an engineering miracle. In 1883, a creative engineer, John Roebling, was inspired by an idea for this spectacular   bridge project. However, bridge-building experts told him to forget it. It just was not possible. Roebling convinced (persuade sb. to do sth. ) his son, Washington, an up-and-coming engineer, that the bridge could be built. The two of them formed an idea of how it could be finished successfully and how to overcome the difficulties. Somehow, they persuaded bankers to provide money for the project. Then, with great excitement and energy, they hired their crew and began to build their dream bridge. The project was only a few months _ when a tragic on-site accident killed John Roebling and severely injured his son. Washington was severely brain-damaged, unable to talk or walk. Everyone thought the project would have to be thrown away, since the Roeblings were the only ones who understood how the bridge could be built. Though Washington Roebling was unable to move or talk, his mind was as sharp as ever. One day as he lay in his hospital bed, an idea flashed in his mind as to how to develop a communication code. All he could move was one finger, so he touched the arm of his wife with that finger. He tapped out the code to communicate to her what she was to tell the engineers who continued building the bridge. For 13 years, Washington tapped out his instructions with one finger until the spectacular Brooklyn Bridge was finally completed. This article mainly tells us   _  .
A. to try your best to save ourselves in an accident
B. never to do dangerous things
C. to study hard the advanced science and technique
D. to fight as long as one has breath
Answer: