What Is the Challenge to Cohabitation

What is the challenge to cohabitation?

A) Relationships between unmarried cohabiting couples tend to be less emotional than those of married couples.
B) Relationships between unmarried cohabiting couples tend to be more conflictual than those of single-parent households.
C) Relationships between unmarried cohabiting couples tend to be more likely to live in poverty than those of single-parent households.
D) Relationships between unmarried cohabiting couples tend to be less stable than those of married couples.