Glad to hear you found the tips and resources helpful —
In terms of 31-2-19 – tough question, in large part because there is a lot of information to deal with —
In general, for questions that require you to critically evaluate arguments, if a majority of answers are sounding attractive to you, that’s, usually a sign that your understanding of the argument flaw isn’t as clear as it can be. This is because the vast majority of wrong answers for these problems are wrong primarily because they do not directly relate to the specific reasoning issue.
And so in situations where you find yourself not being able to recognize many of the answers as being obviously incorrect, I think it can be helpful to recognize that that the issue is probably with your understanding of the gap, so you can try to address it by re-evaluating the conclusion, support, and so on —
Okay, so going back to this specific q — to paraphrase —
The author’s conclusion is that the florist must have made some sort of mistake.
What’s the reasoning?
If the person who sent Drew flowers knows him well, that person would have known Drew prefers violets. And yet the flowers were roses.
If the person who sent Drew flowers didn’t know him well, that person would have sent a card. Drew did not receive a card.
The second part is rock solid in terms of the logic — we know for certain the person would have sent a card and we know for certain Drew did not receive one — and, since Drew did not receive that card, we know that either someone who doesn’t know Drew well did not send the flowers, or if they did, there was some sort of mistake.
The first part is where the gap exists. Knowing someone prefers one thing doesn’t mean you must get that person the thing. My 2-year-old always prefers to eat ice cream, but that doesn’t mean I always give that to her as her meal. For this particular problem, maybe the store had a sale on roses, or the particular occasion is one connected to roses (Valentine’s Day) etc.
So to summarize, the specific gap in reasoning is that the author takes for granted that someone who knows Drew prefers violets must send violets.
In terms of this specific gap between preference and what must be, (B) is the only answer that touches on that particular issue, and if (B) is true, it certainly exposes the issue that knowing someone’s preference doesn’t guarantee a certain action.
I hope that helps clear it up — again, tough problem, and maybe it was something totally different that tripped you up on it! — but as always, I hope you found that useful, and let me know if you have any follow-up — MK