When a producer can produce a good or service at a lower opportunity cost than another, they have:

The concept of comparative advantage is central to economic theory and international trade. When a producer has a comparative advantage, it means they can produce a good or service at a lower opportunity cost compared to others. Opportunity cost refers to the value of the next best alternative that is foregone when choosing to produce one good over another.

For example, if Producer A can produce 10 units of good X or 5 units of good Y, while Producer B can produce 6 units of good X or 3 units of good Y, Producer A has a lower opportunity cost for producing good X relative to good Y. Thus, Producer A has a comparative advantage in the production of good X.

Understanding this principle helps in determining how specialization and trade can increase overall efficiency and economic output, as regions or individuals can focus on producing the goods in which they hold a comparative advantage.

Other options provided do not accurately capture this idea. Absolute advantage refers to the ability to produce more of a good with the same resources, which does not involve the concept of opportunity cost. The terms "negative advantage" and "market disadvantage" are not standard economic terms and do not pertain to the established concepts of economic advantages.