Answer:
A) Because of all the specific requirements there are for astronauts
Explanation:
B doesn't make sense, because there are many people who aren't afraid of going into space
C is true, but there are multiple places where you could become an astronaut. NASA isn't the only place!
D is (really just absurd!) incorrect because, in fact, space research is important! Humans need to know what's in space to protect humanity and to possibly uncover more secrets
A is the answer because you need to meet all the requirements and pass many tests
Ok, I'm sorry (in advance) if the answer doesn't make sense. Just tell me and I will fix it. (I need to go somewhere quickly, so I had to make this a bit quick.)