The human cost of wwi was

a) 5 million casualties.

b) 15 million casualties.

c) 30 million casualties.

d) 40 million casualties.

D) 40 million casualties.

The total number of casualties in World War I was about 40 million, which makes the war one of the deadliest conflicts in human history. Of these deaths, 9-11 million were military personnel, while civilian deaths were about 8 million. The Allies lost about 6 million people, while the Central Powers lost about 4 million. Moreover, about 2 million died from diseases and 6 million went missing.

the answer is b for brother