The correct answer is option-3, 1941. Pearl Harbor, a naval base in Hawaii, was attacked by the Japanese on December 7, 1941. This surprise attack led to the United States officially entering World War II. Option-1, 1935 and option-2, 1939 are incorrect. This is because the attack on Pearl Harbor occurred after these years. Option-4, 1944 is also incorrect. By 1944, the United States had already been involved in the war for several years and had made significant progress towards defeating Japan. It`s essential to understand the historical context and timeline to identify the correct answer in questions related to historical events.