Final answer:
The retail pricing strategy described, where the cost of manufacturing is doubled for wholesale and then doubled again for retail, is referred to as keystone pricing.
Step-by-step explanation:
To determine the retail price of a garment using the strategy mentioned in the question where the cost of manufacturing is doubled to find the wholesale cost, and then doubled again to find the retail cost, is known as keystone pricing. This method of pricing is commonly used in retail to simplify the process of pricing items and ensuring that businesses cover the costs of manufacturing, distribution and selling the items, along with a profit margin. Therefore, the correct answer to the question is c. keystone pricing.