Answer:
blacklisted.
Step-by-step explanation:
As a result of the work of the House Un-American Activities Committee, hundreds of people were "blacklisted"
This is true because House Un-American Activities Committee was made to quickly determine and apprehend suspected individuals who have direct or indirect relationships with the Communist party.
During this period, many people were "blacklisted." This was quickly done to prevent any potential spread of communist ideology.