Final answer:
The b) market price is where supply and demand for a good are equal; this differs from perfectly elastic or perfectly inelastic curves that represent extreme responsiveness or complete unresponsiveness to price changes.
Step-by-step explanation:
The price point at which the supply and demand for a good are equal is known as the market price. In the context of supply and demand curves, the market price occurs where the two curves intersect, indicating that the quantity supplied equals the quantity demanded. It's essential to differentiate this from concepts like perfectly elastic and perfectly inelastic demand or supply curves, as illustrated in economic models. Perfectly elastic demand or supply curves are horizontal lines indicating that any quantity will be demanded or supplied at one specific price, while perfectly inelastic demand or supply curves are vertical lines showing no change in quantity demanded or supplied regardless of price changes.