What economic sectors thrived in California during WWI?

During World War I, California experienced significant economic growth, particularly in agriculture, the film industry, and oil production. Agriculture thrived due to increased demand for food supplies to support both military efforts and the general population, leading to a boom in various crops. The state's favorable climate and vast farmland allowed for a diverse range of agricultural products to be cultivated.

The movie industry, centered in Hollywood, also expanded dramatically during this period. The war created a demand for entertainment as a means for the public to escape the realities of the conflict, thus propelling the growth of the film sector.

Additionally, California's oil industry benefited from the war, as the need for fuel surged with increased military activities and production demands. The state's rich natural resources positioned it as a key player in oil production, further contributing to its economic prosperity during this time.

The other options do not capture the unique combination of sectors that flourished during WWI in California. While finance and telecommunications were important, they did not see the same level of growth or the distinctive interdependence that agriculture, film, and oil exhibited during the war years.