Question

in 1945, what concern did the allies have about invading the japanese mainland with ground forces?
○ they were worried they did not have enough soldiers.
○ they were worried there would be too great a loss of life.
○ they were worried the japanese were developing an atomic bomb.
○ they were worried the japanese had a stronger fleet in mainland ports.

Explanation:

By 1945, Japanese forces had shown extreme fanaticism in defending territory (e.g., battles of Iwo Jima and Okinawa, which had massive Allied casualties). Military planners projected that a ground invasion of the Japanese mainland would result in hundreds of thousands, potentially millions, of Allied and Japanese military and civilian deaths. This was the primary concern that led to the decision to use atomic bombs instead of a full ground invasion.

Answer:

They were worried there would be too great a loss of life.