Comparative advantage means the ability to produce a good or service the ability to produce a good or service

1. more efficiently than another country.
2. with a lower opportunity cost than another country.
3. less efficiently than another country.
4. with a higher opportunity cost than another country.

The right option is; 2. with a lower opportunity cost than another country.  

Comparative advantage means the ability to produce a good or service with a lower opportunity cost than another country.

Comparative advantage refers to when a country produces a good or service for a lower opportunity cost than other countries. Comparative advantage gives a country the ability to produce specific products or services more efficiently at a lower price than its trade partners and to achieve greater sales margins. The benefits associated with buying goods or services of countries with comparative advantage are greater than the disadvantages.