When Children of Comparable Socioeconomic Status Are Compared, Group Ethnic

When children of comparable socioeconomic status are compared, group ethnic differences in IQ test scores are reduced. Which of the following does not explains this result?

A) Some ethnic groups have more "smart genes" than others.
B) IQ test items reflect the cultural heritage of the test creator, most of whom are economically advantaged.
C) When people know that they belong to a group that is said to lack skill in a domain, this makes them anxious when performing in that domain for fear of confirming the stereotype, and they often do poorly as a result.
D) When people are wary of questions posed by unfamiliar adults, many economically disadvantaged children often answer test questions by saying, "I don't know."