Joseph and Cybill Are 24-Year-Old Fraternal Twins Who Are Both

Joseph and Cybill are 24-year-old fraternal twins who are both single. Which one of their following behaviors is most consistent with an evolutionary explanation for sex differences in relationship behavior?

A) Because of his lower parental investment, Joseph is less willing than Cybill to engage in short-term sexual relationships.
B) Cybill engages in more intrasexual competition than Joseph, especially by being physically aggressive toward her rivals.
C) Joseph prefers dating women who are younger than he is, whereas Cybill prefers dating men who are older than she is.
D) All of the above statements are consistent with an evolutionary explanation for sex differences in relationship behavior.