In the short run, the shape of marginal cost, average variable cost and short run average cost curves are:

U-shaped

The correct answer is Option (3) → U-shaped

In the short run, the Marginal Cost (MC), Average Variable Cost (AVC), and Short Run Average Cost (SAC) curves are all U-shaped because of the Law of Variable Proportions.

• Initially, as production increases, efficiency improves — leading to falling costs.

• After a certain level of output, diminishing marginal returns set in, causing rising costs.

Thus, these curves first fall, reach a minimum point, and then rise, forming a U-shape.