Final answer:
The important ships absent at Pearl Harbor during the attack were the aircraft carriers. Their absence saved them from destruction, allowing them to later contribute crucially to U.S. victories, such as at the Battle of Midway, which turned the tide of the war in the Pacific.
Step-by-step explanation:
The type of ships that were absent at Pearl Harbor during the attack on December 7, 1941, and were very important were A) Aircraft carriers. The three Pacific Fleet aircraft carriers, USS Enterprise, USS Lexington, and USS Saratoga, were not in port on that day and thus escaped damage. Although many battleships, destroyers, and other vessels were present and suffered heavy losses, the lack of aircraft carriers in port inadvertently spared the United States from a more severe defeat. In the aftermath, the surviving aircraft carriers played a critical role in the United States' ability to respond and recover from the attack.
It was not until the subsequent Battle of Midway in June 1942 that the significance of aircraft carriers fully came to light. In this battle, the U.S. Navy, having broken the Japanese military code, was aware of a planned attack and used its carriers strategically. As a result, American forces managed to sink four Japanese aircraft carriers, which marked a turning point in the Pacific War. This feat was made possible due to the carrier's absence during the Pearl Harbor attack, allowing them to fight another day and significantly contribute to the eventual U.S. victory in the Pacific.