Why Did Labor Productivity Drop Between 1915 and 1918 in the United

Why did labor productivity drop between 1915 and 1918 in the United States?

A) The United States was involved in WWI and was not focused on industrial production.
B) The main markets were in Europe, which was embroiled in war and not buying products in significant amounts.
C) The male labor force were all fighting in WWI, so production virtually ceased in most industries.
D) Race riots were so violent that they affected and, in some cities, halted factory production.
E) Laborers were so unhappy with working conditions, wages, and hours that they could not be as productive as they were in the past.