Which was the last island that the allies captured before preparing to attack mainland japan?

M

A. Guam

B. Iwo Jima

C. Okinawa

D. Sakhalin

The answer is: Iwo Jima

(Explanation if needed) : Iwo Jima was the last Island the allies had captured before preparing an attack on mainland Japan. Before the complete mainland attack on Japan, the allies deemed it important to capture strategic islands around Japan in order to ensure proper lines of supply and communication.