Final answer:
President Roosevelt likely withheld OSS information from Congress due to fears of espionage, which was a significant concern during his presidency characterized by the Second Red Scare.
Step-by-step explanation:
President Roosevelt may have kept information from the Office of Strategic Service (OSS) from reaching members of Congress (c) because he feared there were spies in Congress. The context of FDR's presidency indicates that there were ongoing concerns about security risks and espionage, particularly related to the communists and other ideological foes. The era is known for the rise of the Second Red Scare, where recently declassified sources disclosed over a hundred spies operating in the U.S., including within the government. With sensitive information potentially being a risk of being passed to adversaries, Roosevelt would have been cautious about sharing intelligence broadly, lest it be leaked by the presence of spies in Congress.