@APG The main issue is that B is confusing the sufficient for the necessary condition. B is sayinh 250+ GUARENTEES the Panthers are self-sustaining. However, the key difference is that IF the population becomes self-sustaining, THEN it must have 250+ (not the other way around). I think it can get confusing because the "must reach at least 250" comes before "if it is to be self-sustaining". But, generally speaking, if there is an "if" (even if it comes secondary) it is a good habit to put it at the front of your notations. Ex. ___ must be Y if it is to be X. Notation: X -> Y