Complete Question Explanation
Assumption. The correct answer choice is (A)
In this stimulus two facts are presented as premises and then a causal conclusion. The stimulus concludes that the government "was, on average, considerably more lax in enforcing" laws during the second period mentioned. The stimulus offers evidence that there were less citations per year, but the government is never mentioned in the premises. The government's enforcement or lack thereof is a new element in the conclusion, which demonstrates a gap in the reasoning. The stimulus assumes that the government's lack of enforcement is the cause of an effect it demonstrates without any evidence. This is a Defender assumption question, so the correct answer is one that tries to "defend" the conclusion by eliminating other possibilities opened by this gap. In a causal reasoning assumption question, any answer choice that negates another possible cause is the correct answer.
Answer Choice (A): This is the correct answer choice. Use the negate and destroy technique and remove the "not" in this answer. If the decrease was caused by a decrease in violations, then the conclusion does not follow. If there were fewer violations, the decline in violations is not the result of the government's lack of enforcement. This answer choice must be true, i.e. it is necessary, in order for the conclusion to follow.
Answer Choice (B): This answer choice attempts to trick the test taker by slyly inserting one simple word, "minor." The stimulus deals explicitly with "serious violations" so this answer, when negated, does not affect the conclusion at all.
Answer Choice (C): This answer choice could possibly be true, but it is not necessary for the conclusion to follow. If you negate this answer choice, it has no affect on the conclusion of the argument.
Answer Choice (D): This answer choice introduces a different type of reasoning with its "should" phrasing. Whether they should or should not is not an issue in this stimulus; the causal connection is what we are dealing with.
Answer Choice (E): This answer choice introduces information about citations prior to 1971. By negating this answer you will see that it does not affect the stimulus in any way. We are only dealing with the decline in citations in the years mentioned, prior to 1971 is irrelevant.