The US military combat unit size was drastically reduced by the end of World War I.
Answer: Option A
Explanation:
As it is well known that the defeat of Germans in the World War I is only due to the interference of US at the end of war. The US army fought bravely and large amount of money was utilized for transport of convoys to defeat the German army.
After successful victory over the German, the troops were called back to home. But the loss in economy due to the war lead to absence of any welfare schemes for the war veterans. And thus this lead to displeasure among the army people who fought in the war.
So, the after years of US saw a decrease in the size of the combats followed by continuous strikes conducted by the war veterans for their educational and service readjustment benefits. This lead to political disturbances followed by unemployment in army leading to reduction in size of combats.