What part of the federal government writes laws?

What does this answer mean?

Congress writes the federal laws. USCIS accepts three ways to say it: Congress, the legislature, or the legislative branch.

Article I of the Constitution gives all of the federal government's lawmaking power to Congress, which has two parts: the Senate and the House of Representatives. A bill, which is a proposed law, has to pass both the House and the Senate. Then it goes to the president.

If the president signs the bill, it becomes law. If the president vetoes it, Congress can still make it law by voting again, with two-thirds of both the House and the Senate agreeing. That process is one of the checks and balances between the branches.

Legislative comes from legislate, which means to make laws, so "the legislature" and "the legislative branch" both point to the same place: Congress.

At the interview, the shortest answer is "Congress."