Final answer:
A partial adjustment to the amount owed by the customer for goods that were not returned, but did not fully meet the customer's expectations is referred to as a sales allowance.
Step-by-step explanation:
The correct answer is c. allowance.
A partial adjustment to the amount owed by the customer for goods that were not returned, but did not fully meet the customer's expectations is referred to as a sales allowance. It is a deduction or reduction in the amount owed by the customer, given as compensation for the goods not meeting their expectations. This can be seen as a form of customer service and a way to maintain customer satisfaction.