Question

a court is born!
what if there were only one court in the entire united states? would that be enough? the constitution of the united states created just one court: the supreme court. but you probably already know that today there are lots of courts. what happened?
well, for one thing, each state has its own state court system. but somehow, a whole network of federal courts also came into existence...
follow the link to see a transcript of the constitution. scroll down until you find article iii. read the beginning of section 1.
https://www.archives.gov/founding-docs/constitution-transcript

1. according to the constitution, who has the power to create federal courts that are below the supreme court?

Explanation:

Article III, Section 1 of the U.S. Constitution states that Congress has the authority to establish inferior (lower) federal courts, as the Constitution only mandates the Supreme Court explicitly.

Answer:

The United States Congress has the power to create federal courts below the Supreme Court.