Answer:
A) Radio was the most popular source of mass entertainment of World War I.
Step-by-step explanation:
The impact of radio on the entertainment industry during world war I was very important in shaping the country's ideology towards particular propaganda. the military used propaganda in the Radio and broadcast it people listen to the radio where various jobs and offers were offered which help them to get jobs during wartime.
After the war, many people use the radio as the major medium of Entertainment because various advertisements and other offers were broadcasting on Radio.