From the article:
Sociologist Alexandria Walton Radford was interested in the college choices of ambitious and high-performing high school students from different class backgrounds. Using a data set with about 900 high school valedictorians, she asked whether students applied to highly selective colleges, if they got in, and whether they matriculated.
She found a stark class difference on all these variables, especially between high socioeconomic status (SES) students and everyone else. Over three-quarters of high SES valedictorians (79%) applied to at least one highly selective college. In contrast, only 59% of middle SES and 50% of low SES valedictorians did the same. Admission and matriculation rates followed suit.