Answer:
C. Having him injure character A without a fight.
Step-by-step explanation:
The actions of the characters are vital to the formation of opinion among the audience as Plato has explored in his book "The Republic". He says that art has the power to evoke emotions(Pathos in Aristotelian term) of the audience witnessing it. In this case also if character B injures character A without a fight, it would lead to a very negative impact on the audience as they believe that the actions have to be justified. For example, if the protagonist of a work leads to certain circumstantial actions, there must be some inherent causes to those actions and hence, the action is justified. But here, the action by character B could not be justified as s/he injured character A without any fight or personal animosity which would help the audience to sympathize with character A and vice versa to character B.