@ConqueringLSAT since it's a NA question, you're looking to find answers that's necessary. Usually ones that don't seem to support or strengthen right away but one the argument couldn't be true without

@M1ckeymina true. the "significant numbers" part doesn't seem necessary, as long as they could relocate, it should work. But it's the best answer choice left.

@Nickgigs (D) isn't necessary because you don't need every single student to "not improve" to have overall student to "not improve". Necessary means as long as the possibility of overall student "not improve" exists.

In hindsight, applying the negation directly would avoid all the overthinking. By using negation, you have "If most or all of the teachers hired in the school district were underqualified, hiring more teachers may improve the achievement of students in the school district." This obviously doesn't destroy the conclusion, no not necessary

@OverheadHopefulStructure If "plant species indigenous to tropical rain forests" are studied by scientists, any substance of medicinal value contained in them will eventually be discovered. I don't recommend diagramming if it makes sense to you by just reading it

I think here it assumes teachers want to teach students in a way that helps them. This however, wasn't stated, but obviously necessary.

The explanation says (D) can be fixed by removing the word "primary". That is, it's necessary that at least some steel manufacturing plants rely on electricity as a source of energy in the steel-manufacturing process. Is this really the case?

Checking with the negation technique, we get "no steel manufacturing plants rely on electricity as a source of energy in the steel-manufacturing process".

If electricity can't be used for the steel-manufacturing process, would there still be any electric bills for the steel-manufacturing plant? If not, Can the heat-converted electricity be of any other use? If so, would that use necessarily not save any money?

The premise doesn't state that the electric bills of steel-manufacturing plants result from the steel-manufacturing process. It may result from other different process that's part of the plant, and with the electric bills that come with it being reduced, money may be saved.

@SoniaKulkarni negation of A is: In spite of the difficulties encountered, at one time or another people have not tried to domesticate each wild large mammal species.

Premise talks about each of the wild large mammal species that "seemed worth domesticating".

The negation of A doesn't contradict with the premise.

@Eliana Warner Probably not. We don't know if Plesiosauromorph was able to find enough food to meet the caloric requirements dictated by its body size, so the contrapositive isn't triggered. Hence, you couldn't get to the conclusion.

@Nickgigs

"The design of Japanese gardens should display harmony with nature" is one of the premise.

"Rocks found in nature also vary widely in appearance" is another premise.

The conclusion is "rocks chosen for placement in such gardens should vary widely in appearance".

Necessary condition refers to a conditional relationship (if..., then...), which isn't present here. So there isn't one here. Instead we're looking for a necessary assumption.

my thoughts (could be wrong)