This is Must be True question that we should be able to refer the right answer choice to the passage.
Information regarding nobles are:
1) they possess hundreds of serfs as opposed to much less in US slave owners.
2) they didn’t see serfs directly much but had intermediaries.
Now, let's go to the answer choice.
A) What made them abolish serfdom is not given
B) While the fact that management of serf was done by intermediaries in Russia was given, whether there was any change that went through this system or not is not provided. Unsupported. (30-34)
C) 'volnenie' is introduced as smaller rebellion. Whether they agreed to their demand or not is not given (50-54)
D) This is it. The second reason we've discussed above supports this. (30-34) (Correct)
E) Whether nobles "hastened" the abolition or not is not given in the first place. So, whether abolition was the response to the rebellion or not is unsupported.