I believe the correct answer is C.
1. legs like rubber
2. walk like chickens
3. hands like pieces of wood
4. fast as a steam locomotive
First of all, it implies that this is occurring in the future, but not extremely far like 10,000 years from now; it's a reasonable amount of time away. Second of all, because of the word "finally," we can infer that everyone in that society is equal and that the general consensus about the equality is good. Because the author uses the word "finally," it makes it seem like they've finally made it through a struggle to reach equality.
The definition of compulsory is required by law or a rule; obligatory.
C.
None of the others seem to be true.
