During the late 1940s and 1950s, many Americans feared communist "subversion." Which of the following is the B?

All of the above, and every one of them a proven US tactic, historically. Let's also not forget E) Deliberately targeting civilians in a military campaign (My Lai, Operation Menu, Fallujah, Nangarhar, Amiriyah Blockhouse, IranAir 655 etc) and F) Backing insurgencies & coups to overthrow governments and install a more US-friendly leader (Venezuela, Cuba, Surinam, Haiti, Indonesia, Chile, El Salvador, Iran, etc etc)