The passage tells us: B -> SO. We are then told that the insect only did sting once, which is our necessary condition. This is used to conclude that the insect must be a bee, which is our sufficient condition. So, the passage is using the necessary condition (SO) to conclude the sufficient condition (B), which we know is invalid. The correct answer choice will follow this same pattern of reasoning.
Answer choice (C) tells us: O+BP -> MEC We are then told that the painting is never moved with extreme care. This is used to conclude that the paintings must not be old and brittle. This is different from the passage, which uses the necessary condition to conclude the sufficient condition. Instead, (C) uses the negated version of our necessary condition (which is the sufficient condition of the contrapositive) to conclude the negated version of our sufficient condition (which is the necessary condition of the contrapositive). Therefore, (C) is incorrect.
Does that make sense? Please let us know if you have any other questions!
