Maybe a more simplified way of picking between C & D - it might be true that C weakens more than D, but only if we make certain assumptions in the background about how C works. Simply judging the answer choices on their face, D weakens w/o having to jump through as many hoops.

This is such a great post! Thanks for sharing your approach. Looking forward to playing with this a bit on my next PT.

This question would be a lot easier if the first sentence didn't exist. The key to this question is seeing past the first sentence and realizing it doesn't offer us anything useful.

This question is hard because the flaw is subtle. One way to think about the flaw is that we don't know the proportional impact of snow + ice v. sea + land. It could be that because there is so much more sea + land than snow + ice as is, the decrease of snow + ice would be negligible, even if it all disappeared. Thus, we need an answer that strengthens the importance of snow + ice cover in cooling temps by reflecting sunlight. C does a really good job of underscoring the importance of snow + ice by saying "actually, land + sea would make the situation worse if they were the only things to exist."

Question 26. I interpreted uncertainty as meaning no, rather than just not being sure. This conflation made it impossible to therefore distinguish between A and D. So, because I understood uncertainty as = No, and A is a solid No, I chose A.

A is a great answer choice if this was a necessary assumption question and has a conclusion in the stimulus that said "therefore, the people who lived at this site either cultivated plants earlier than anyone else or ate diets that were more varied that anyone else."

But it wasn't, womp womp. Very stupid mistake.

I don't actually like JY's explanation here-- think there is an easier way to explain it.

We don't need to worry about B, C, and E because the rule isn't relevant to people we don't know are 1st term board members. So, just picking between A and D.

If you do a quick translation of the stimulus, you can very quickly eliminate A and prove D. Key here is fluency with translation rules.

Fboard--> A or All; /A & /All --> /Fboard

A only gives us half the sufficient condition, so obviously we cannot draw the conclusion.

D gives us both parts of the sufficient condition, so we can draw the conclusion.