i'm interested as well! :)

I also got this question wrong (I chose D), so I'm going to attempt to explain it just so that I can better understand it myself hahaha. As for why "An act or omission..." isn't the conclusion, I saw it as the principle that the actual main point was founded on. For example, a principle can be "A student cheating would be unethical" and the main point can be "Students shouldn't cheat." The one that relies on the other is the main point; ex) Q: "Why shouldn't students cheat?" A: "Because a student cheating would be unethical." It wouldn't make sense the other way, like Q: "Why would it be unethical for a student to cheat?" A: "Because students shouldn't cheat." The principle feeds and justifies the other point, and it would be the same if you plugged in the statements from this question. I THINK...

The "first lawyer's questioning" is a modifier of the witnesses, basically clarifying that they want you to resolve the seeming discrepancy that exists within that group. So you're still expected to take the results of both cross-examinations to do that, otherwise there would be no conflict to resolve :)

I'm confused (I got the correct answer); the stimulus says, "However, vacuum tubes' maximum current capacity..." -- doesn't that immediately absorb the initial smaller subset of "small experimental vacuum tubes"? Wouldn't it only be an issue if it were the other way around?

fr