Answer:
Because they were thought to be spreading the Communist activities.
Explanation:
House Un-American Activities Committee was the committee was founded on May 26, 1938. The purpose of this committee was to investigate the Communist activities during the early years of the Cold War.
During the Cold War, the United States formed this community to stop people from spreading hate slogans against the government and army who were fighting against Germany.
After the formation of this committee, the members targeted Hollywood film industry thinking it to be the spring communist activities. Ten Hollywood screenwriters and directors were called for investigation which was denounced by them. These screenwriters and directors were also known as Hollywood Ten, who were imprisoned and blacklisted from working in Hollywood. Later, in the 1960s, they were removed from the blacklist.
So, the correct answer is that the Hollywood industry was thought to be the primary source of communist activities that is why HUAC targeted them.
