Option 1 -> Marginal cost equals total cost only when quantity is 1, not related to rising AC.
Option 2 -> Marginal cost equals average cost only at the minimum point of AC curve.
Option 3 -> When MC < AC, the average cost is falling, not rising.
Option 4 -> When MC > AC, each additional unit costs more than the average, pulling the average upward.
Hence, Marginal cost > Average cost -> When marginal cost exceeds average cost, each additional unit produced costs more than the current average. This higher marginal cost pulls the average cost upward, causing it to rise. This is a fundamental relationship: MC intersects AC at AC's minimum point; when MC > AC, AC is rising; when MC < AC, AC is falling. Think of it like test scores - if your new score (marginal) is higher than your current average, your average goes up. -> correct