Hard question implications of the postulates of special relativity?

Question

Einstein performed thought experiments to understand the implications of the postulates of special relativity because...

he was too poor to afford the necessary experimental apparatus.

he could not carry out the experiments alone and no other scientists would work with him.

did not know how to build an apparatus that would test his ideas.

the speeds involved are too large to easily generate.

Answer 1

D) The speeds involved are too large to easily generate.

Answer 2

The last one. Although the second to last is also true I think the last one is a slightly clearer answer.

Answer 3

He needed ten years of mathmatical calculations when he estimated the time of the calculations.But he died 2-3 years

after the estimation.If his hand written calculations of these 2-3 years are available,there are a few people who can continue.

Answer 4

So what is/are your question(s)?