The Point of Tangency Between the Short-Run Average Total Cost

The point of tangency between the short-run average total cost (SRATC) curve and the long-run average cost (LRAC) curve occurs

A) at the point of minimum SRATC.
B) at a point where average total cost is falling but the marginal cost is rising.
C) at a point where both the average total cost and the marginal cost are rising.
D) at an output level for which the quantity of the fixed factor is optimal.
E) only when the LRAC curve is at its minimum.