So, just to clarify, would the rationale for the correct answer essentially be that (along with all the assumptions you list) "since energy efficient appliances are (likely) used en masse by tenants who don't pay electricity individually, then it is less likely that energy will be conserved as ...

Are we supposed to assume that these chemicals are initially "harmless" or that the dilution process renders them as such? That specific detail made me identify (A) as Out of Scope, given that nothing in the passage alludes to their basic toxicity.

To me, this sort of question encapsulates the shift in difficulty of LR over the past few years. More are being crafted that leave the test taker to make large assumptions that, in my experience, really haven't been incorporated into LR in year's past. It's a little unfortunate.