The following questions present a sentence, part of which or all of which is underlined. Beneath the sentence, you will find five ways of phrasing the underlined part. The first of these repeats the original; the other four are different. If you think the original is best, choose the first answer; otherwise choose one of the others.
These questions test correctness and effectiveness of expression. In choosing your answer, follow the requirements of standard written English; that is, pay attention to grammar, choice of words, and sentence construction. Choose the answer that produces the most effective sentence; this answer should be clear and exact, without awkwardness, ambiguity, redundancy, or grammatical error.
According to government health statistics, Americans born before 1925 develop obesity. by the age of 65 only 8 percent of the time, but 35 percent of those born since 1950 did so by age 35.（）
A. Americans born before 1925 develop obesity by the age of 65 only 8 percent of the time, but 35 percent of those born since 1950 did so by age 35
B. only 8 percent of Americans born before 1925 developed obesity by the age of 65; if they are born since 1950, 35 percent develop obesity by the age 35
C. only 8 percent of Americans born before 1925 developed obesity by the age of 65; of those born since 1950, 35 percent developed obesity by the age of 35
D. obesity develops by the age of 65 in only 8 percent of Americans born before 1925, and by 35 by the 35 percent born since 1950
E. of Americans born before 1925, only 8 percent of them have developed obesity by the age of 65, but 35 percent of those born since 1950 do by the age of 35