At first I didn't love C... BUT a friend help give a clearer perspective on what C needs to do in order to be correct, and what it does not need to do.

We need to add support or strengthen the modern historians challenge. At first glance may sound like a typical strengthen, however, "challenge" indicates that the modern historians are not making a positive argument that Caligula is or is not anything, they are just trying to weaken the traditional view's argument.

In other words, adding support in this context does not mean providing evidence that Caligula is not a cruel, insane tyrant. We don't have to prove he isn't cruel, insane, or a tyrant. We don't have to prove he is good, average, or anything else. Our goal is simply to help challenge, or weaken, the evidence provided by the traditional view.

We are told 1) there is little documentation and 2) that it comes from enemies. We want to attack the reliability of the documentation and/or the credibility of the enemies who wrote it.

Answer C says that the descriptions of specific acts attributed to Caligula (not his general/overall behaviors) are very similar to those found in other, earlier writings (hmmm plagiarism? or at least strongly influenced?). To be clear, this doesn't *prove * the descriptions were copied, and it doesn't have to! But it calls into question whether the descriptions are fair or maybe stolen from already existing sources by biased writers. That might not be a strong argument, but were not the ones making it. The fact a counter argument now possibly exists, means we have helped someone else to challenge the traditional view. If eliminating competing hypotheses strengthens an argument, then we have weakened the traditional view's argument by providing opportunity for additional competing hypotheses. Goal accomplished.

Controversial/Fun Analogy:

The traditional view that Star Wars is a sci-fi classic has been challenged by some modern viewers. They point out that "classic" is kind of an ambiguous term, and that much of the positive media influence comes from Disney related sources. We add:

Specific thematic elements attributed to Star Wars are very similar to elements attributed in earlier stories to other sci-fi franchises alleged to be classics like Dune. (The 'Chosen One' boy with unique space-religious power, living on a sand planet run by a fat, sluglike tyrant, becomes the leader of a rebellion against a galactic empire who fights back sending masked/armored anonymous troopers to attack the rebels' hidden bases. Surprise--the Chosen One boy has special sister too, etc...)

We did not prove anything, but we definitely muddied the water and opened the door to some counter arguments!

May the Force be with you!

I had to sit with this one for a minute.

But, I came to the understanding that:

If cats were identical in which proteins they had, then it would be impossible for there to exist a person that has cat allergies and is not allergic to every cat because every cat would have the protein that they are allergic to.

However, the stimulus tells us that there are cats that do not cause reactions in some people with cat allergies: "it is common for a given cat to cause an allergic reaction in some—but not all—people who are allergic to cats."

In other words, there does exist a person that has cat allergies but who also does not react to certain cats. Meaning those cats who don't cause reaction lack a protein found in other cats which do cause reactions to that person.

Therefore answer C.

I was glad to see lots of other comments. This question actually seemed really straight forward to me but maybe I'm looking at it wrong?

I simplified the logic as:

If (Greater heat resistance) AND (comparable) then preferable

And we are told that although some vacuum tubes meet the first half of the sufficient condition (Greater heat resistance), all vacuum tubes fail the second required condition (comparable).

As a result of failing the full sufficient condition, it is insufficient to trigger the necessary condition. In other words, even if a vacuum tube has greater heat resistance, none of them are comparable, therefore none of them are preferrable.