If the “phenomenon” in (A) is the 1/3 pass rate, (A) is wrong because there’s no evidence that the pass rate caused the curriculum to be implemented. The curriculum was in effect for “several years.” There’s no evidence that a 1/3 rate existed before the curriculum was used.

The author does not rely on a lack of evidence that the quality of instruction has increased. The author relies on the results of a survey. Those results do not establish that there’s a lack of evidence of an increase in the quality of instruction.

The results suggest the curriculum is below average (b/c of below-avg pass rate). The author concludes this shows there was a decrease in quality. This is flawed because the evidence of pass rate in one year doesn’t tell us whether this rate decreased after the new curriculum.

The author isn’t required to specify the national average rate. We accept as a premise that the 1/3 pass rate last year is below the national average. The exact number that is the average doesn’t impact the reasoning.

The author relies on survey results. The survey results do not establish that anything was required to produce a particular pass rate. The author’s conclusion also does not assert that anything was required. So there’s no confusion of requirements with sufficient conditions.