Nina and Mitch, a cohabiting couple, have been deeply attracted to each other since their college years. This gives them both a deep and fulfilling sense of sexual well-being. After graduating from college, Nina has been able to find a good deal for an apartment for them, and have agreed to share the rent. Seeing that they are extremely cooperative and committed to each other, Mitch has come to believe that the thread that binds them together is sacred.
The deep desire for each other and the sexual fulfillment in the relationship between Nina and Mitch points to which characteristic of commitment?

a) Sexual well-being
b) Attraction
c) Serial monogamy
d) Moral-normative perception
e) External constraints