The correct answer is: B. joint costs
Joint costs are costs that are incurred in the production of multiple products at the same time. They are not separable into the costs of the individual products. For example, the cost of slaughtering a cow would be a joint cost if the cow is used to produce both beef and leather.
Separable costs are costs that can be identified with a particular product or group of products. For example, the cost of processing beef into steaks would be a separable cost.
Main costs are the most important or significant costs in a production process. They are often the costs of raw materials or labor.
Split-off costs are the costs incurred after a joint process has been completed and the products have been separated. For example, the cost of shipping beef to a grocery store would be a split-off cost.