A firm's total variable costs depend on which of the following?

Total variable costs are directly influenced by the production techniques employed by a firm and the prices of the variable inputs used in the production process. Variable costs are expenses that change in direct proportion to the level of output, such as raw materials, labor, and energy costs, which can vary based on how much of the product is being produced.

The production techniques play a crucial role because different methods can utilize variable inputs to varying degrees of efficiency or cost-effectiveness. For example, using advanced machinery might lower variable costs by reducing labor hours needed to produce each unit. Additionally, the prices of variable inputs—like the cost of raw materials or hourly wages—immediately affect total variable costs; an increase in input prices raises overall costs, while a decrease lowers them.

In contrast, options that focus solely on the amount of output or the firm’s production techniques without considering the prices of inputs would provide an incomplete understanding of variable costs. Fixed costs are also not relevant here, as they remain constant regardless of output level and do not affect total variable costs. Therefore, the comprehensive view that includes both production techniques and input prices substantiates why the correct choice is affirmatively linked to variable costs.