To infer means to get to a logical conclusion based on some information. In this case, we know who haunts the bears (John) and how he does it (the traps) as well as some risks involved in hunting bear from the open door of a helicopter. With this information, it is not possible to talk about John's feelings, so A is incorrect; B is also incorrect because it doesn't mention anything about studying the bears. On the other hand, we know that John is hunting bears even though we don't know why or his feelings about them or about the fact of hunting.
