What are your options? If you listed them I can help! :)
This is what we call a "red scare." The first Red Scare happened after World War I -- which also was the time when communists came to power in Russia. (The Bolshevik Revolution began in Russia in 1917, during the time of the war.)
The second Red Scare came after World War II. During the war, the USA and the USSR had been allies -- although always somewhat uncomfortable allies. Together they fought to defeat German and Japanese aggression. But the USA and the USSR had very opposite views to one another. So after World War II ended, there was great fear in America again about the infiltration of communist ideas around the world.
That is because these were people who usually had some wealth and were successful. It was done to prevent slaves or migrants or women or anyone similar from attaining political power. It was a way of keeping the status quo as it was and make the old land owners some sort of a new political elite.
C. civil laws.
A is wrong because there’s nothing criminal about interactions. B is wrong because it doesn’t say in the homes of US citizens. D is wrong because it doesn’t say outside of the US/