Final answer:
The most likely accurate causal explanation for U.S. involvement in World War II is option C) The United States entered World War II because both Japan and Germany declared war on it.
Step-by-step explanation:
The most likely accurate causal explanation for U.S. involvement in World War II is option C) The United States entered World War II because both Japan and Germany declared war on it.
Although Japan's attack on the U.S. naval base at Pearl Harbor served as the immediate cause for the U.S. entry into the war, tensions had been building between the U.S. and Japan prior to the attack, and Germany had already declared war on the United States. Additionally, the United States had been seeking ways to assist its European allies, such as Britain, in fending off potential German invasions.