An example of a type of American household that is becoming more common is (D) a man and a woman who are not married.
Cohabitation, an arrangement where two people who are not married but are involved in an intimate relationship live together, continues to rise in America. In 2016, about 18 million adults in the United States were cohabitating. On the other hand, marriage rates have fallen in the last few years. Couples usually resort to cohabitation due to fear of divorce but they also choose to live together in order to save money and to spend more time together.
The cohabiting population includes all age groups. Since 2007, the number of cohabiting adults aged 50 and older grew by 75%; however, the average cohabiter is between 25-34 years old.