Answer:
The boy is a bully because he is instigating a fight and taunting to cause trouble.
Explanation:
relative clause
it modifies noun phrase by some grammatical tools
example
my friend who is coming from America is coming to the dinner
here who is used to indicate the noun phrase
subject verb agreement
A subject and a verb must agree, even when other words or phrases come between them.
example
The flock of geese is flying south for the winter.
The subject is flock, so the verb should be is flying.
B. It makes way more sense than the others
