Which of the following was an incident where hundreds of innocent civilians were brutally murdered by american soldiers?
a.) tet offensive
b.) salt
c.) watergate scandal
d.) my lai massacre

My Lai Massacre was the mass murder conducted by a unit of the U.S. Army on March 16, 1968 of 347 to 504 unarmed citizens etc.

My Lai Massacre is one of the most horrific incidents against civilians during the Vietnam War. During My Lai march in 1968, a company of American soldiers killed many from the South Vietnamese hamlet. It is believed that 500 were killed including the children, women, and the elderly. 

The answer is crop yield.