What was a result of the use of chemical weapons during World War I? Tanks and aircraft were developed to counter the effects of chemical weapons.
Trenches were used to protect soldiers from chemical weapons in battle.
Many nations agreed to stop using chemical weapons after World War I.
Doctors developed treatments that made chemical weapons obsolete.

Many nations agreed to stop using chemical weapons after World War I.

Explanation:

The use of chemical weapons during World War I had devastating effects on humanity; both on the aggressors and aggrieved. It killed hundreds of thousands and gave many others, after-effects that lasted them decades.

The Chemical Weapons Convention (CWC) control treaty was put into force on 29th April 1997 where production, stockpiling, and use of chemical weapons was outlawed.

C: Many nations agreed to stop using chemical weapons after World War I. on edge 2021

the answer is c.

hope this : )

b is the answer i am assuming