Answer:
The correct answer is A. Nixon invaded Cambodia without telling Congress.
Step-by-step explanation:
The bombing and the subsequent invasion of Cambodia by the American forces were carried out during Operation Menu, from March 1969 to May 1970.
Nixon decided to keep the missions a secret. The attack on the "neutral" Cambodia would surely bring serious debates in the United States Congress, negative criticism in the media and anti-war protests on American campuses.