How can comparative advantage yield gains from trade?

What will be an ideal response?

Comparative advantage refers to the ability to produce a good or service at lower opportunity cost compared to other producers. If nations specialize in producing goods in which they have a comparative advantage and trade at rates of exchange that are more favorable than the opportunity costs they would have faced without trade, then they can obtain more goods for consumption with trade than they could have obtained for consumption without trade. These consumption gains are the gains from trade.