Which of the Following Does Research Indicate to Be True

Which of the following does research indicate to be true of the romantic and nonromantic relationships single people are involved in?

A) People who reach sexual intimacy quickly are more likely to be in romantic relationships.
B) Sexual activity in nonromantic relationships is associated with high relationship quality.
C) People who have had more prior partners are more likely to be in nonromantic relationships.
D) Reduced investment increases the likelihood that the relationships will become intimate.