题目选项分析

According to a recent survey, marriage is fattening. Cited as evidence is the survey's finding that the average woman gains 23 pounds and the average man gains 18 pounds during 13 years of marriage.

The answer to which of the following questions would be most relevant in evaluating the reasoning presented in the survey?

【选项】Why was the period of time studied in the survey 13 years, rather than 12 or 14?