Santiago wants to buy some milk and a box of cereal. If he buys 2 quarts of milk at $1 per quart, the box of cereal costs 75 cents. If he buys 3 quarts of milk at $1 per quart, the box of cereal is free. For Santiago, the marginal cost of the third quart of milk is

Goods whose income elasticities are negative are called

A) normal goods. B) superior goods. C) inferior goods. D) complements.

The above figure shows the market for anti-freeze. The government imposes the sales tax shown in the figure on sellers. The sales tax on anti-freeze decreases the quantity of anti-freeze that automobile owners purchase by

A) 0 gallons. B) 1000 gallons. C) 2000 gallons. D) 3000 gallons.