What campaign was known for its poster "I Want You," primarily used during WWI?

The campaign known for the iconic "I Want You" poster, featuring Uncle Sam, is the Committee of Public Information. This organization was established in 1917 by the U.S. government to promote interest in World War I and encourage public support for the war effort. The "I Want You" poster was one of the most successful recruitment tools, effectively conveying a sense of patriotism and urgency to enlist in the military.

The Committee of Public Information employed various forms of media, including posters, films, and speeches, to mobilize the American public. This campaign played a significant role in shaping public opinion during the war and exemplified the government’s effort to rally citizens around the cause. The other options listed were associated with different functions and roles in American society; for instance, the American Red Cross focused on humanitarian aid, the War Advertising Council engaged in public service advertising, and the United War Effort was a broader coalition aimed at coordinating war efforts but did not produce the famous poster attributed to the Committee of Public Information.