Answer:
C: mobilize
Step-by-step explanation:
Congress passed the Selective Service Act, which Wilson signed into law on May 18, 1917. The act required all men in the U.S. between the ages of 21 and 30 to register for military service. Within a few months, some 10 million men across the country had registered in response to the military draft.
mobilize: (of a country or its government) prepare and organize (troops) for active service.
ex: "Russia is in no position to mobilize any time soon