Many deaths in World War I resulted from

the war lasting longer than was initially expected

chemical weapons such as mustard gas

the decreased use of trench warfare

radiation poisoning from reactors leaking

Chemical weapons such as mustard gas

The correct answer is B) chemical weapons such as mustard gas.

Many deaths in World War I resulted from chemical weapons such as mustard gas.

During World War 1, chemical weapons were used massively and killed many people. Chemical gas was used primarily in the enemy trenches. There were many kinds of chemical gases such as tear gas, chlorine, and mustard. Mustard gas was a volatile oily liquid. The gas could remain active for weeks. That is why it was so lethal.