Question

the primary duty of the legislative branch is to
make federal laws for the united states
enforce the laws for foreign nations
appoint all the supreme court justices

Explanation:

The legislative branch in the US is responsible for making laws at the federal level. It doesn't enforce laws for foreign nations (which is not its jurisdiction) and doesn't appoint all Supreme - Court justices (the President nominates and the Senate confirms).

Answer:

make Federal laws for the United States