Chang Industries has 2,800 defective units of product that already cost $30 each to produce. A salvage company will purchase the defective units as is for $13 each. Chang's production manager reports that the defects can be corrected for $22 per unit, enabling them to be sold at their regular market price of $29. The $30 per unit is a:

Multiple Choice

Incremental cost.

Sunk cost.

Out-of-pocket cost.

Opportunity cost.

Period cost.