Which word refers to an agreement between the states?

a tariff

a compact

reserved power

emancipation

Among the options given on the question the correct answer is option B.

A compact

Explanation: The word 'Compact' refers to an agreement between the states. According to the constitution, in United States when two or more states comes to any agreement this is called as the interstate compact.

An interstate compact can be signed on many aspect between the states. But there are certain rules and regulations for this kind of compact. According the Article 1, section 10 of the United States Constitution, "No State shall, without the Consent of Congress ... enter into any Agreement or Compact with another State."

There are some model compact already approved by the government and any states can join to this. Moreover, states can submit the compact into the Congress prior to joining the compact.