5.) does not make sense to me the answer choice that was selected did not seem like a contrapositive, it seemed more like a mistaken negation. Can someone please explain to me why answer choice C is correct. Mr. Lin says that in answer choice B) he eliminates because it starts off with " for" but so does answer choice C)

5.) does not make sense to me the answer choice that was selected did not seem like a contrapositive, it seemed more like a mistaken negation. Can someone please explain to me why answer choice C is correct. He says that in answer choice B) he eliminates because it starts off with " for" but so does answer choice C)