The correct response to how the post–World War II Red Scare changed over time is:
Surveillance of American citizens got more intense.
During the initial phase of the Red Scare, there was significant fear and paranoia about communist influence, which led to a series of actions that included investigations and the establishment of anti-communist organizations. Over time, especially during the McCarthy era, this surveillance and scrutiny escalated, leading to more aggressive tactics against perceived communists and sympathizers.