Help please with history i been struggled

What does it mean when world war one is referred to as a “total war”

Supporters of using the atomic bomb at the end of world war ii believed that a japan might win the war if the bomb was not used. b americans were tired of war and the us should end it quickly. c russia was developing a bomb and the us needed to use it first. d japan was developing a bomb and the us needed to use it first.

List three reasons why explorers began to explore new, and old areas. [[ps: doesn't explicitly say where. i think it's more in general.