Which of the following statements would extreme right-wing reactionaries and extreme left-wing radicals most likely agree upon?A. Those that are...

If both left wing radicals and
right wing reactionaries have to agree to this, it comes down to A and
C.  Between those, I would argue that C is the more likely
answer.

B and D are statements that only left-wing people
would agree with and so you can easily rule those out.

A is
probably not the best answer because a really extreme right-wing reactionary might well
be a monarchist.  Such a person might not agree that those best able to rule should
rule.  Instead, they might say that those who traditionally hold power should continue
to hold that power regardless of whether they are truly the most able
people.

C is probably acceptable to both.  Left wing
radicals believe in things like the dictatorship of the vanguard party.  There were no
real elections in the Soviet Union.  At the same time, right wing reactionaries would
believe that the mass of people are too stupid to rule themselves and that elections,
therefore, are not a good way of getting a good
government.

For these reasons, C is the most likely
answer.