Your answer would NOT be A because Boo hasn't been out of his house in about 15 years, the children have never even seen him, so there is no way that he could threaten them.
It is B because :
Scout, Jem, and Dill are afraid of Boo because they hear some pretty bad stuff about him. They've heard that he stabbed his father with scissors, and Boo hasn't been out of the house for nearly 15 years. All of this makes Boo seem pretty scary.
So, your answer is B) They have heard rumors that he is dangerous.
It isn't C because Atticus actually tells them NOT to be scared of Boo, because Boo has never done anything wrong.
It isn't D because the children are in fact extremely scared of Boo.
So, once again, your answer is B) They have heard rumors that he is dangerous.
I believe that b is the correct answer. the other sentences are proper and there isn’t anything that needs to be added. for b, it seems like there should be something added after it or something like he was before the sentence starts
