The most influential change in events on the outcome of the battle for Iwo Jima would be if the Navajo code talkers had not been used for communication.
During World War II, particularly in the Pacific theater, secure and efficient communication was crucial for coordinating attacks and movements. The Navajo code talkers developed a complex code based on the Navajo language, which was unbreakable by the Japanese and allowed for rapid and secure transmission of information.
Without their contributions, communication among American forces would have been slower and less secure, potentially leading to miscommunications, delays, and increased vulnerability to enemy actions. This could have significantly affected the coordination of the strategy and tactics employed during the battle, ultimately impacting the outcome of Iwo Jima.
The other options provided, while interesting, relate to different contexts (the Korean War and Vietnam War) or events (Pearl Harbor) that would not have had the same direct impact on the Iwo Jima operation itself.