How Did New Weapons Such as the Machine Gun Affect

How did new weapons such as the machine gun affect warfare in World War I?

A) They led to trench warfare that resulted in unprecedented casualties for all involved.
B) They gave the Allied powers an enormous advantage over the underequipped Germans.
C) The prospect of total carnage deterred the officers in charge from ordering massive assaults.
D) They gave individual soldiers more fire power and better odds for surviving the war.