题目选项分析

The quality of unrefined olive oil is not actually defined in terms of acidity, yet extensive tests have shown that the less free oleic acid an unrefined olive oil contains per liter, the higher its quality. The proportion of free oleic acid that an olive oil contains is an accurate measure of the oil's acidity.

If the statements above are all true, which of the following conclusions is best supported by them ?

【选项】Free oleic acid is the only acid that unrefined olive oil contains.