Fixed costs remain constant regardless of output level

Steps:

• Recall that total cost = fixed costs + variable costs.
• Fixed costs (e.g., rent) stay the same whether production is zero or high.
• Variable costs (e.g., materials) rise with output.
• Match definition to choices: identify costs unchanged by output.

Why A is correct:

• Fixed costs exist even at zero output, per the definition in economics where they are output-independent.

Why the others are wrong:

• B describes variable costs, which fluctuate with production.
• C refers to decreasing average costs, not fixed costs.
• D defines average fixed costs, not fixed costs themselves.

Final answer: A