CAT Critical Reasoning Practice question with Solution 74

We’re introduced to a foul-sounding substance called “leachate,” which develops when water permeates a landfill site. The most explicit thing we’re told about leachate is that it escapes into the environment whenever the landfill’s capacity to hold water is exceeded, and it only escapes into the environment when the landfill’s capacity to hold water is exceeded (that’s the meaning of the “if and only if” statement in the second sentence). We’re also told that a method to dispose of leachate must be found; currently, most leachate is sent to sewage treatment plants, but some sewage treatment plants can’t handle leachate.

We need a good inference based on this mess, and it comes out of the “if and only if” statement. We know that if the landfill’s capacity to hold liquid is exceeded, leachate is certain to escape into the environment, which means that answer choice (E) is inferable: if leachate doesn’t escape into the environment, the landfill’s capacity hasn’t been exceeded.

(A) The stimulus does say that leachate generally escapes into the environment in unpredictable quantities, and that not all sewage plants can deal with leachate, but nowhere implies that the two facts are related; there’s no reason to think the ability to predict the escape of leachate would help with the disposal problem.

(B) contradicts the passage, which says leachate only escapes into the environment when a landfill’s ability to hold liquids is exceeded.

(C) is unsupported; the stimulus says “not all” treatment plants can handle leachate, not that none of them can.

(D) The stimulus doesn’t say that any leachate is actually sent to any of the plants that can’t handle it; only that such non-leachate-friendly plants do exist.