Which of these terms best describe the official foreign policy of the united states at the start of wwii i n 1939

The correct term would be neutrality.

When World War II started in 1939, the United States did not want to get involved in any major foreign conflict. This policy of neutrality would allow them to stay out of the war for the time being. The US Congress passed three different neutrality acts in Congress during the 1930's to ensure this policy remained. This included cutting off trade with nations involved in wars and avoiding entering war zones with any American merchant ships.