What was the main purpose of the food administration during World War I

The U.S. Food Administration was the agency responsible for the administration of the U.S. Army overseas and Allies' food reserves during the United States' participation in World War I. One of its important tasks was the stabilization of the price of wheat on the U.S. market.

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."