For countries participating in a regional trading agreement, what makes this type of agreement significant to the countries involved?

Group of answer choices

a. It may cause countries uninvolved in the agreement to maintain importing goods with the countries involved in an agreement.

b. Its purpose is to eliminate barriers to the movement of labor, goods, and capital across those countries involved in it.

c. It might dampen the free market forces within each of the countries not associated with the agreement.

(please no explanation I need quick answer asap)