Before they married, Bill and Tanya were determined to

have an egalitarian relationship, sharing household tasks and childcare. But after the birth of their first child, Jason, Tanya found herself doing the majority of the childcare, and Bill found himself working longer hours at his job than ever. This is an illustration of what theoretical principle or concept?
a. androgyny
b. the parental imperative
c. the biological clock
d. gender-role crossover

B