Use the excerpt below to answer the question.
The battle of Iwo Island [Iwo Jima] has been won. The United States Marines by their individual and collective courage have conquered a base which is as necessary to us in our continuing forward movement toward final victory as it was vital to the enemy in staving off ultimate defeat.
—Admiral Chester W. Nimitz
Why was this battle important to U.S. forces?
A: It forced Japan’s government to negotiate treaty terms.
B: It blocked a massive Japanese assault against Australia.
C: It supported long-range bombing missions against mainland Japan.
D: It led to the unconditional surrender of Japan’s military.