The correct answer is C. The invasion of Cambodia by U.S. forces
Step-by-step explanation:
On May 4th of 1970 students from Kent State University in Ohio gathered to protest against the United States military forces as the U.S. had bombed and invaded Cambodia which had been announced by Richard Nixon as part of the Vietnam War many U.S. citizens already opposed, because of this the invasion of Cambodia made meany including the student of this university to organize protests. Additionally, this protest led to the death of four students and many others were injured the National Guard decided to shot against the crowd of students incident that was known as Myas 4 massacre. Therefore, the demonstrations at Kent State University in May 1970 were held do protest against the invasion of Cambodia by U.S. forces.