it took me forever to figure out the difference too but after reading it over and over I see how D is correct. D is actually (for the most part) a decent argument while C isn't once you break it down.

The difference between C and D is that in C "Frogs" is a necessary condition while in D it is the sufficient condition. So what C is doing is drawing a conclusion after affirming the necessary while in D it is doing so after affirming the sufficient condition (Which is a valid thing to do).

Think about it this way for example: In C, all it is saying is that no other animals live in the lagoon other than frogs. It is very possible in this scenario that there are over 1000 frogs on the island and only 2 of them live in the lagoon and those 2 frogs are the only animals to be known to actually live in the lagoon. So drawing the conclusion that just because the owls eat frogs from the island must mean they got it from the lagoon would be a terrible conclusion in that scenario.

D is worded differently. In D, its possible that plenty of animals live in the lagoon including frogs. But in D, they are explicitly stating that if you have a frog from the island, it essentially HAS to have come from the lagoon since that is the only place frogs have been discovered on the island.

It refers to the difficulty of the passage/game as a whole. The column that says "question difficulty" refers to the difficulty of that specific question

I recommend purchasing a book called " the loophole in LSAT logical reasoning" by Ellen Cassidy. It has a lot of really helpful tips and tricks when it comes to LR and its helped me substantially increase my score in that section.

I had this same exact thought process too and it's the only reason I didn't select D.

But then I tried thinking about this way:

Let's say that a large portion of mail is correctly addressed but damaged in transit. If that actually were the case then it wouldn't be true that nearly all correctly addressed mail arrives with in two days since a large majority of that mail is damaged in transit, which is in direct contradiction with what the first part of the stimulus says. When it says that the only instance that doesn't happen is when it is damaged in transit, it's basically indirectly telling you that that doesn't happen most of the time, but rather in rare instances.

Basically C is saying that just because you offer a rebate on the item it's not going to entice someone who wasn't going to use the item before to all of a sudden use it now.

Think about it this way, if answer choice C said that the rebate WOULD attract purchasers who otherwise might not use Grow Again, then that means the rebate itself is attracting more customers and thus might actually be good for the company. But since it ISN'T doing that, then the rebate is pointless essentially.

It's not that we are to assume they could hang on to their job connections per se, but rather assume that maybe it was the fact that it was their already previous work experience in journalism that helped them get jobs after graduation rather than their education from the school itself. AC A weakens the argument by essentially saying "Woah there dean not so fast, you ever stop to consider the fact that more than half of these students already had experience in the field before even enrolling in your school which may be the reason they were able to land jobs after graduation?"