For a monopolistically competitive firm in long-run equilibrium,
- the demand curve must intersect the average total cost curve at the ATC curve minimum.
- the demand curve must be tangent to the average total cost curve at the ATC curve minimum.
- at the profit-maximizing quantity, the demand curve must intersect the average total cost curve.
- at the profit-maximizing quantity, the demand curve must be tangent to the average total cost curve.
