Here's the problem: My father likes turnips, but not potatoes, which he says are tasteless. So it is not true that whoever likes potatoes likes turnips.

LSAT Demon says the original argument confuses sufficient for necessary but I just cannot see how. I think I understand sufficient vs necessary; if you live in L.A. you live in California, but if you live in California it doesn't mean you surely live in L.A., etc etc—but I cannot see how anything like that applies here. Is it just that it actually switches the sufficient assumption (liking potatoes) with the necessary one (liking turnips)? Please help lol

Edit: Here are the answer choices

A: This book is not a paperback, but it is expensive. So it is not true that some paperbacks are expensive.

B: Although this recently published work of fiction has more than 75 pages, it is not a novel. Thus, it is not the case that all novels have more than 75 pages.

C: All ornate buildings were constructed before the twentieth century.…