Question

What formal power would the president use to enact an economic stimulus bill?

sign a bill which Congress has passed
propose a bill for Congress to pass
address Congress to gain their support for the bill
use social media to influence public opinion

Answer 1

Sign a bill which Congress has passed.

Reason: formally enacting a stimulus into law is done by the president's constitutional signing (or veto) power. Proposing legislation, addressing Congress, and using social media are persuasive/informal tools, not the formal act that makes a bill law.