(A) At one point of time, Galileo was the only person who believed that the earth was not the center of the universe. WRONG - cannot prove this statement.
(B) A majority of scientists do not agree with the theory of evolution. WRONG - Dubious at best, this statement is far from correct let alone provable
(C) It is difficult to prove the theory of evolution with certainty. CORRECT - this is mentioned in the argument - "the fact that it is very difficult to prove how a group of non-living elements can combine together and give rise to life."
(D) When Galileo stated that the sun and not the earth was the center of the universe, he was called insane by his compatriots. WRONG - Not provable but a real-world trap - maybe this was true but we cannot prove it using the info given in the argument.
(E) Everything that, at one time, seems impossible will, at some point in the future, become possible. WRONG - Dubious statement too extreme.

Hence Option (C) is our choice.

Ask if something is still unclear.

Regards