单选题 A study of the difference in earnings between men and women in the country of Naota found that the average annual earnings of women who are employed full time is 80 percent of the average annual earnings of men who are employed full time. However, other research consistently shows that, in Naota, the average annual earnings of all employed women is 65 percent of the average annual earnings of all employed men.
Which one of the following, if also established by research, most helps explain the apparent discrepancy between the research results described above?

A、 In Naota, the difference between the average annual earnings of all female workers and the average annual earnings of all male workers has been gradually increasing over the past 30 years.
B、 In Naota, the average annual earnings of women who work full time in exactly the same occupations and under exactly the same conditions as men is almost the same as the men's average annual earnings.
C、 In Naota, a growing proportion of female workers hold full-time managerial, supervisory, or professional positions, and such positions typically pay more than other types of positions pay.
D、 In Naota, a larger proportion of female workers than male workers are part-time workers, and part-time workers typically earn less than full-time workers earn.
E、 (E) In ten other countries where the proportion of women in the work force is similar to that of Naota, the average annual earnings of women who work full time ranges from a low of 50 percent to a high of 90 percent of the average annual earnings of men who work full time.

【正确答案】 D

【答案解析】[解析] 对解决分歧型的题，就是要找产生分歧的差异原因。在所有受雇的妇女中，既包含有全职工作者，又包含有兼职工作者，当从事兼职工作的妇女比例较高，且兼职工作的工资较低时，就可以解释两组结果的差异，因此(D)为正确答案；(A)、(B)、(C)和(E)均为无关选项。