THE CORRECT ANSWER IS E. THE ORIGINAL SENTENCE CONTAINS THE PHRASE...
41. The correct answer is E.
The original sentence contains the phrase "ordered that", which
requires a clause containing the subjunctive. However, the original
sentence has "should" instead. Moreover, it is illogical to test a lake
or stream "for mercury levels". Instead, one tests the mercury
levels of the lake or stream.
The only choice to address all these issues is E.