The Democratic Republic of Congo (then known as the Belgian Congo) was important to the Allies during World War II primarily because it provided uranium that would be vital in building the atomic bomb. The uranium mined in the Congo, particularly from the Shinkolobwe mine, became a critical resource for the Manhattan Project, the U.S. effort to develop nuclear weapons. This strategic resource played a significant role in the outcome of the war, as the successful development of the atomic bomb ultimately contributed to the defeat of Japan.
The other options provided—having a force of disgruntled men against the Allies, enabling France to use propaganda for recruits, and the importance of controlling a territory previously held by Germany—do not highlight the same level of strategic significance as the discovery and use of uranium for atomic weaponry. Therefore, the correct response emphasizes the crucial role of the DRC in supplying uranium.