The recently injured athlete's drug test was positive for marijuana. Although the athlete insisted that he had not used the drug, he did admit to spending some time at a party where others were smoking. The doctor, however, insisted that contact of that sort could not result in a positive indicator.
Which of the following, if true, would contribute most to an explanation of the results of the drug test?
(A) Taking large amounts of inuprofen can result in false positives for marijuana.
(B) Secondhand smoke exposes innocent bystanders to a variety of toxic chemicals.
(C) Excessive exercise has been found to mask certain effects of marijuana use.
(D) The athlete had tested positive for amphetamines three years earlier.
(E) The team doctor sends all test samples out to an independent laboratory.
(McGraw-Hill)