The correct answer is: B. Fixed cost
Period costing is a method of accounting that assigns costs to a specific time period, rather than to a specific product or service. This means that fixed costs, which are costs that do not change regardless of the volume of production, are assigned to the time period in which they are incurred.
Prime cost is the sum of direct labor and direct materials costs. Direct labor is the cost of labor that is directly associated with the production of a product or service. Direct materials are the costs of materials that are directly used in the production of a product or service.
Variable cost is a cost that changes in proportion to the volume of production. For example, the cost of raw materials is a variable cost, because the more products that are produced, the more raw materials will be needed.
Semi-variable cost is a cost that has both fixed and variable components. For example, the cost of electricity is a semi-variable cost, because there is a fixed cost for the electricity that is used to power the factory, and a variable cost for the electricity that is used to power the machines that produce the products.