Demand Curve Characteristics for Wills' Product

Steps:

• Identify the type of demand curve based on price sensitivity.
• Recall that perfectly inelastic demand means quantity demanded remains constant regardless of price changes.
• Compare options to standard elasticity definitions.
• Select the matching description without additional data.

Not enough information to confirm the demand type for Wills' product, as no price-quantity data or elasticity calculation is provided.

Why D is correct:

• Assumes the given correct option; perfectly inelastic demand is a vertical curve where quantity demanded is fixed (elasticity = 0), per economic definition.

Why the others are wrong:

• A: Unitary elasticity shows proportional price-quantity changes (elasticity = 1), not fixed quantity.
• B: Downward-sloping straight line implies elastic or inelastic but not perfectly so.
• C: Perfectly elastic is horizontal, with infinite quantity response to price.

Final answer: D