题目选项分析

Adoption rates vary a great deal based on demographic statistics. Depending on the socioeconomic status of prospective adoptive parents, their chances of successfully adopting a child can vary by up to a factor of two hundred. Ultimately, it is therefore clear that wealthier families are much more likely to successfully adopt.

The answer to which of the following questions would best help evaluate the effectiveness of the above argument?

【选项】What are the average income levels of families who successfully adopt compared to unsuccessful families?