Long-run equilibrium features adjusted supply meeting demand at zero economic profit.

Steps:

• Distinguish short-run supply (upward-sloping, fixed factors) from long-run supply (horizontal at minimum ATC, full adjustment).
• Short-run equilibria show temporary profits or losses, driving entry or exit.
• Entry shifts supply right until it intersects demand at the long-run supply curve.
• Long-run point is where demand meets horizontal long-run supply, ensuring zero profit.

Why B is correct:

• B is the intersection of demand and horizontal long-run supply, per perfect competition model where P = min ATC = MC.

Why the others are wrong:

• A: Short-run point above long-run supply, indicating positive profits and entry.
• C: Short-run point below long-run supply, showing losses and exit.
• D: Intersection of short-run curves only, not adjusted for long-run entry/exit.

Final answer: B