Equilibrium supply elasticity at price OP

Steps:

• Identify OP as the equilibrium price where supply equals demand.
• Examine the supply curve's slope at OP to assess responsiveness to price changes.
• Calculate elasticity as percentage change in quantity supplied over percentage change in price.
• Determine that at OP, the curve's shape yields equal percentage changes, indicating unit elasticity.

Why C is correct:

• Price elasticity of supply equals one when a 1% price increase leads to a 1% quantity supplied increase, matching the diagram's unit elastic point at OP per elasticity formula: $\eta_s = \frac{\% \Delta Q_s}{\% \Delta P} = 1$.

Why the others are wrong:

• A: Diagram shows revenue as area under price line, not comparable to all consumption costs/benefits without full welfare analysis.
• B: Consumer surplus is triangle above OP, but no scale given to compare definitively to revenue.
• D: Market clears at intersection, but OP labeling alone doesn't confirm it's the exact clearing price without demand curve details.

Final answer: C