A. The Supply Curve
Explanation

A supply curve shows the relationship between the price of a good and the quantity producers are willing to sell, holding all other factors constant. The law of supply states that as the price rises, the quantity supplied rises, and vice versa, giving the curve its upward slope.

Each point represents a price and quantity pair from the supply schedule. As the price of gasoline rises from $1.00 to $2.20 per gallon, the quantity supplied increases from 500 to 720 million gallons. Higher prices make production more profitable, which encourages producers to supply more.

The supply shift slider explores what happens when non-price factors change (input costs, technology, number of sellers). Moving along the curve is a change in quantity supplied (price-driven); shifting the entire curve is a change in supply (driven by other factors).

Elasticity
Supply Schedule
Price ($/gal)Qty (M gal)ΔPΔQ
Shift Supply
H-shift = change in quantity supplied at every price level. V-shift = change in the price needed to bring forth every quantity.
Selected Point
Key
Supply curve S
Original S (when shifted)
Price and quantity points
\( Q_s = f(P) \quad \text{with} \quad \frac{\Delta Q_s}{\Delta P} > 0 \)