Answer:
D
Explanation:
D) [this ogre] had a riding habit like Mrs. Bullfrog's, and
also a green silk calash dangling down her back by
the strings
The answer to your question is A) Therefore.
The answer would be A. whose
B. who's would not make sense in this situation because who's is a contraction which means 'who is'. If that was to be used in the answer, the sentence would be, "Margaret wants to knwo<em> who is</em> bike this is," which makes no sense whatsoever
Whose shows possession
Hope my answer helped! :)