I too am in the same boat. And I'm unsure on how to fix it.

I think the reason B is wrong is that it (kind of) attacks the premise of 'the tea is high in caffiene', which is not what we should be doing when solving weakening questions (but rather weaken the support). My rationale when I chose B was, if they're drinking it in the evening there MUST not be as high of a caffeine concentration... which doesn't make sense now.

I think your rationale for not choosing C is actually correct. If you assume that a narcotic tea leaf will make you drowsy and concentrate less, wouldn't it make sense that Akabe people consume it in a very small amount to minimize those effects? ie to not "destroy their surefootedness". Maybe they consume it in just the right amount so that they don't feel the downer effects of the narcotic but do get a small narcotic high to make their daily tasks more enjoyable?

From my understanding from watching all these videos, we need to leave the premise and conclusion as is and work with them to weaken the support of the argument.

What bothers me about this explanation is that he says "what does fish have to do with the premise", which seems contradictory to explanations of solutions to other weakening questions. We are explicitly taught to not attack the premise or the conclusion, but rather, the support. Answer choice A does not attack the premise or the conclusion. Plus, if there is a word for fish, it does CAST a doubt on whether or not the Proto-Indo-Europeans lived near oceans/seas. It doesn't destroy the argument, but it could weaken it.

In other answer choices for weakening questions we have to make bold assumptions all the time, but this time it's wrong to assume that fish come from the sea/ocean?

I am not refuting B as the correct answer choice but simply stating that the explanation to why A is wrong is somewhat contradictory to previous answer explanations of the same question type.

send me the link!!