Which of the following is true in long-run equilibrium for a firm in a monopolistic competitive industry?

A) The demand curve is tangent to marginal cost curve.
B) The demand curve is tangent to average cost curve.
C) The marginal cost curve is tangent to average cost curve.
D) The demand curve is tangent to marginal revenue curve.

Tangent

A straight line that touches a curve at a single point without crossing it at that point.

Long-run Equilibrium

A state in a market where all firms are making normal profits, with no incentives for entry or exit, and all factors of production are variable.

Demand Curve

A graphical representation showing the relationship between the price of a good and the quantity demanded by consumers.