Why Not A? Not CM -> PSB

Hi, I was not able to rule out answer A. The stimulus guides us to invoke the sufficient condition - "not catering to masses" (Not CM). When doing so, I could not arrive at the conclusion that the bookstore was able to profitably sell books below market prices (PSB). In the video explanation, the instructor states that it "could be true" by invoking PSB as the sufficient condition instead of the necessary condition. My contra positive diagram looked like this: No CM & No Exclusive Access --> No HSV -> No D-> No PSB My positive argument looked like this: PSB --> D--> HSV--> CM or EA, or both Why is PSB assumed to be more sufficient than Not CM? If we start with Not CM in the contrapositive, we see that concluding PSB is not a possible option in the logic chain above. The missing premise is that EA exists; without this, we cannot make a valid conclusion that satisfies the necessary condition - Profitably selling books below market price (PSB). Hence, I couldn't eliminate A from the list. Is there a concept or rule that I'm not applying somewhere? Anthony