As part of the league of nations’ disarmament effort, members ?

a.) made wartime killing illegal.
b.) destroyed weapons.
c.) stopped manufacturing guns.
d.) declared an end to war.

The correct option is B. 
League of nation disarmament effort was an effort made by the members of the league of nations to bring about the abolition or reduction of weapons in each country after world war 1. The effort was geared at drastically reducing the quantity of weapons in each country.

The correct answer is B. Destroyed weapons

All of these countries were under colonialism (colonial rule). Hopefully, this is somewhat helpful.