[单选题]The paragraph is followed by an incomplete phrase or sentence which summarizes the main idea of the paragraph. Choose the missing words of the phrase or sentence.


The edible soybean is a vegetable of high protein content containing 35 to 40 percent of protein and from 18 to 20 percent of oil. It is well supplied with vitamins and mineral salts. Compared with some other foods, soybeans contain one and one-half times as much protein as cheese and peas, eleven times as much protein as milk.

The （） of soybeans.