Final answer:
Cohabitation is defined as two people of the same or opposite sex living together as unmarried partners. It has become more popular in recent years, with approximately 28 percent of men and women cohabitating before their first marriage. Contrary to some studies, cohabitation has little effect on the success of a marriage.
Step-by-step explanation:
Cohabitation is defined as two people of the same or opposite sex living together as unmarried partners. This makes option A the correct answer. Cohabitation has become more popular in recent years, with approximately 28 percent of men and women cohabitating before their first marriage. Therefore, option B is incorrect. Contrary to option C, most couples today do believe it is a good idea to live together in order to decide if they should get married. Lastly, while some controversial studies suggest that cohabitation decreases the likelihood of success in marriage, the most recent research shows that cohabitation has little effect on the success of a marriage. Therefore, option D is incorrect.