otal of all direct costs is termed as .a.cost of production.b.cost of sales.c.prime cost.d.works cost.

To determine the correct answer to the question, let's analyze the terms provided.

1. Cost of Production: This refers to all costs involved in making a product, including direct and indirect costs. It includes materials, labor, and overhead costs but is generally broader than just direct costs.

2. Cost of Sales: This typically refers to the costs directly tied to the sale of goods or services, which includes direct costs associated with the production of goods sold.

3. Prime Cost: This specifically includes all direct costs associated with manufacturing, such as direct materials and direct labor. It does not include indirect costs.

4. Works Cost: This term usually encompasses the total cost of manufacturing a product, including both direct and indirect costs.

Given these definitions, the term that accurately represents the "total of all direct costs" is c. prime cost.

Final Answer: c. prime cost