Out of All the People Listed, Who Is Least Likely

Out of all the people listed, who is least likely to marry?

A) Andy and Jessica, a Caucasian couple who live in a low socioeconomic area of Dallas, TX.
B) Darian and Beth, an African American couple who are both attorneys in San Francisco and live in an upscale, gated community.
C) Andre and Trish, an Asian American couple who are cohabitating.
D) David and Olivia, a Caucasian couple who are both from upper middle-class families and currently in college.