​Heterosexual contact is the leading source of HIV infection in _______.

A) ​the United States
B) ​Africa
C) ​Eastern Europe
D) ​Russia

Heterosexual Contact

Sexual interactions between individuals of the opposite sex.

Leading Source

The most important or prominent origin or provider of information or materials in a particular context.

HIV Infection

An infectious disease triggered by the human immunodeficiency virus that targets the immune system, potentially resulting in acquired immunodeficiency syndrome (AIDS).