I'd say the answer requires context. A, D or E could all be correct depending on whether the speaker's focus is on scientific revolutions (as opposed to social revolutions), social revolutions (as opposed to scientific revolutions) or if they aren't focusing on either.
I'd say the answer requires context. A, D or E could all be correct depending on whether the speaker's focus is on scientific revolutions (as opposed to social revolutions), social revolutions (as opposed to scientific revolutions) or if they aren't focusing on either.