<em>ran-- so; they--created is the answer / adverbs.</em>
Im pretty sure its c but don't know for sure
I feel that the above mentioned topic sentence is a good topic sentence because it includes the author's opinion and a limited topic that tells the readers what the text is going to be about without outright telling them.
(For the second post, I think you're supposed to finish the topic sentence's paragraph.)
Theory, as in hypothesis, idea, educated guess