The correct answer of the given question above would be WORLD WAR II. World war II had the largest number of Americans served in the armed forces. T<span>he War Department including civilians and those in uniform was somewhere between 16 and 20 million it was about 24% of the population at the time. Hope this answer helps.</span>
As the name suggests, Indus Valley is not a mountain range, and it is a valley around the Indus river instead. The remaining options are all mountain ranges.
