PT 13, S2, Q24

@smilde11 let's diagram the first part of the passage. Remember to always translate "Unless" as "If not": Not NBS ==> CFV not CFV ==> NBS The passage tells us that NBS is true. But you'll notice, not CFV is a SUFFICIENT condition of NBS, not a necessary condition. So it is not the case that not CFV must be true, Thus (A) is correct, since we are looking for the one answer choice that COULD be FALSE. If we diagram the last sentence of the passage, we get: NBS ==> DACA ==> SMI. So since we know NBS is true, SMI must be true. Thus (C) is incorrect.

I thought "unless" introduces a necessary condition. So CFV==> Not NBS At least thats what I have from my notes from the sufficient and necessary video. so the reverse would be NBS==> Not CFV

Unless is tricky, but I like to treat it as just a term "if not" so, in that conception, it introduces the negative of a sufficient condition. I generally find it much simpler to replace the word unless with if not, and it makes the sentence way easier to understand, and maybe diagram if we choose to do so.