Why is this propaganda poster from 1917 encouraging Americans to "plant and raise" vegetables?

Responses

AThe United States was at war against Japan.
The United States was at war against Japan.
BThere was a lack of farmers in the country.
There was a lack of farmers in the country.
CAll available food was needed to support the war effort.
All available food was needed to support the war effort.
DThe Dust Bowl had destroyed most farmland in the United States.

CThe United States was at war during World War I and needed all available food to support the war effort. Planting and raising vegetables would help increase food production domestically.