- Water temperatures in the polar seas are the same today as they were a century ago
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Unlikely that melting process has begun
I think the key to this question is fully understanding that word, "begun." If we think about "begun" then I think it makes it a little bit easier to think of possible objections to this argument. What if it takes awhile for the water temperature to change? We are talking about a big area of water so that would definitely make sense! In addition, what if the air temperature is hotter than it was a century ago? This could also totally happen and, if the air temperature is hotter, it could explain why - even though the water temperature is the same - the melting process has in fact begun. After thinking about these objections, I'll go to the answer choices.
- (A) We are more interested in these present levels and what caused them or how they relate to the polar caps melting/water being the same temperature. We don't really care how it affects the marine life; we instead care about this X factor that has affected the water temperature.
(B) Yea but has the melting process actually begun?! The argument says "no" but we are looking for something to say "well maybe, yes!" We don't care about what happens after the melting process has occurred, we care about the melting process itself and how it affects water temperature.
(C) This is a great answer....for a strengthen question. This looks very attractive because it relates to something that I predicted: if the air temperature has varied then maybe this would be the cause of the same water temperature despite the polar caps melting. However, this would actually be the opposite of what we want because it rules out an alternate explanation, precisely the effect of a really good strengthener.
I do want to add as well that this might not even be strong enough for an actual strengthen question, had this been one. The reason is because we actually don't know what "varied" means. Does "varied" mean that the air temperature is higher than it was before? Does it mean that the air temperature is lower? We don't know.
(D) This looks really good! Let's break this down. We are talking about the "temperature of water containing melting ice." Perfect. That is the subject of the argument. Apparently that temperature "remains constant" until "all the ice...has melted." The key word here is "all." Because (D) tells us that we need ALL the ice to melt before the temperature is impacted, this brings in some level of doubt to the scientists' contention. The scientists say that "the melting process probably not begun." Yet this answer choice basically says "it's impossible to know unless all the ice has melted." So what we have here is proof that the scientists claim cannot be proven yet. We don't know how unlikely it is that the polar caps have begun melting. Why? Because we won't know if the process has begun to occur until the process has already been completed. I know that's all slightly confusing but I hope that helps.
(E) We don't really care about the temperature near the equators and, if anything, this just boosts the premise that the water temperatures are the same by showing that the water temperatures are basically the same across the board. Yet this doesn't affect our knowledge of whether or not the polar caps have melted.
