Lucas and Chloe Have Been Together for Two Years

Lucas and Chloe have been together for two years. They are fully committed to one another and their relationship. However, they have chosen to have an "open"relationship, wherein romantic and/or sexual involvement with others outside the relationship is accepted. Although their family and friends don't understand the relationship, Lucas and Chloe feel that what they have is strong. This relationship illustrates the idea that some romantic relationships

A) are voluntary, and some are not.
B) are based on love, and some are not.
C) are exclusive, and some are not.
D) involve same-sex partners, and some do not.