Which government body would be responsible for laws that related to trade between two states?

state
federal
municipal
special purpose district

Federal

Explanation:

The US Constitution gives the federal government, more specifically the Congress, the power to make laws that regulate trade between two states. Such duty is outlined in Article I, Section 8, Clause 3, also known as the Commerce Clause:

The Congress shall have power (...) To regulate commerce with foreign nations, and among the several states, and with the Indian tribes;

sorry ill come back