An exception to the general decline of infectious diseases in the u. s. is the increase in after 1960.

The answer to the question stated above is:

An exception to the general decline of infectious diseases in the U.S. is the increase in sexually transmitted diseases after 1960.
Sexually Transmitted Diseases (STDs) is also referred to Sexually transmitted infections (STIs). An example of STD is Hepatitis B. It is considered an STD because it can be spread through sexual contact.

Cwould be the answer