Final answer:
Chlamydia is the most common bacterial STI in the United States, with about 2.9 million infections occurring in 2015. It is most common among young people, particularly those between the ages of 15 and 24.
Step-by-step explanation:
Chlamydia is the most common bacterial sexually transmitted infection (STI) in the United States. It is caused by the bacterium Chlamydia trachomatis. In 2015, an estimated 2.9 million chlamydia infections occurred in the United States. Chlamydia is most common among young people, with about two-thirds of new cases occurring in people between the ages of 15 and 24.