This economics question tests your understanding of economic models and analysis. The step-by-step answer below applies the relevant framework and explains the reasoning.
ScanSolve AI Answer
Step 1: Identify the cause of the U-shaped long-run average cost (LRAC) curve. In the long run, all inputs are variable, so cost curves reflect returns to scale (how output changes when all inputs scale proportionally). Step 2: Explain returns to scale and their effect on LRAC. Increasing returns to scale: output rises more than proportionally → economies of scale → LRAC decreases (downward slope). Constant returns to scale: output rises proportionally → LRAC constant (flat bottom). Decreasing returns to scale: output rises less than proportionally → diseconomies of scale → LRAC increases (upward slope). This produces the U-shape of LRAC. Step 3: Rule out other options. A and B (Law of variable proportion / diminishing returns): Short-run concepts (one input fixed), explain U-shaped short-run AC curve, not long-run. C (Law of diminishing marginal utility): Applies to consumer utility, not firm production costs. The U-shaped long-run average cost curve is explained by return to scale. D