Answer:
d. It improved the ability of the United States to provide military support to the Allies.
Explanation:
The Selective Service Act was enacted by the 65th Congress of the United States of America and it became effective on the 18th of May, 1917 after being signed by President Woodrow Wilson. This act gave power to the federal government of America to recruit both US citizens within 30 days of reaching the age of 18 or immigrants within 30 days of arrival to USA, into the national army for their services in the World War I.
Basically, the act stated that all men who were between the age of 18 and 25 to be registered with Selective Service.
Hence, the statement which best describes how the passage of the Selective Service Act affected World War I is that, it improved the ability of the United States to provide military support to the Allies.
