The correct answer to this open question is the following.
Although there are no options attached, we can say the following.
You did not specify the moment in US history of this scenario, but we can assume you are talking about the Pearl Harbor attack of December 1941.
FDR choose to go before the entire Congress rather than simply call the congressional leaders to the White House for a briefing because he considered that the historic moment needed a speech before Congress, being one of the branches of the Federal government, and to ask for a declaration of war against Germany.
After the Japanese Air Force attacked the ships on the Navy base of Pearl Harbor, Hawaii, President Woodrow Wilson decided to drop the foreign policy of neutrality and to participate in World War II. The US entered WWII on December 11, 1941.
