1. Single people are more likely than married couples to be in touch with friends, neighbors, siblings, and parents. Many good studies have shown this.

A. That single parents are more likely than married couples to be in touch with friends, neighbors, siblings, and parents has been shown in many good studies.

B. Many good students have shown that single parents are more likely than married couples to be in touch with friends, neighbors, siblings, and parents.

C. Single parents are more likely than married couples to be in touch with friends, neighbors, so they have been shown in many good studies.

D. Many good students have shown why single parents are more likely than married couples to be in touch with friends, neighbors, siblings, and parents.