In which battle of the Pacific Theater was the Japanese naval fleet decisively defeated?

The Battle of Midway, which took place in June 1942, is significant because it marked a turning point in the Pacific Theater during World War II. This battle resulted in a decisive defeat for the Japanese naval fleet, which lost four aircraft carriers, a heavy cruiser, and over 300 aircraft. The loss of these critical assets severely weakened Japan's naval capabilities and shifted the balance of power in the Pacific towards the Allies.

The outcome of the Battle of Midway not only demonstrated the effectiveness of American naval intelligence and code-breaking efforts but also boosted the morale of U.S. forces and laid the groundwork for subsequent offensive operations in the Pacific. The subsequent battles mentioned in the other options, such as Iwo Jima and Okinawa, were significant, but they were more about land engagements rather than naval fleet confrontations. The Battle of the Coral Sea was also a critical naval battle, but it ended in a strategic stalemate with significant losses on both sides, rather than a decisive victory for the U.S.