Which action is an example of the united states using ?

 A. Refusing to trade with a country until it improves its human rights record.

Explanation:  The question asked about using economic influence as a tool of foreign policy.  Trade and commerce are economic activities.  Imposing  trade sanctions against a country is a way of exercising economic influence. In this case, the economic influence is being used to try to achieve a foreign policy goal -- the recognition of universal human rights.

As for the other responses ...

the real gdp increased by 4.1%

explanation:

might not be right, i think i'm correct, but i might be thinking of last quarter

although world war i began in 1914, the united states did not join the war until 1917. the additional firepower, resources, and soldiers of the u.s. to tip the balance of the war in favor of the allies. remaining neutral. when war broke out in 1914, the united states had a policy of neutrality.