This graphing calculator illustrates the demand for spaghetti dinners served in all the restaurants in a community. Start by clicking on the Reset button to make sure that the price of tacos, the price of wine, and the average income in the community are set to their initial values. With the initial price of $15 per spaghetti dinner, write down the quantity demanded. Then reduce the price of tacos to $2 and increase the average income in the community to $60,000. Observe the new quantity demanded.

7.2. What can you conclude from the change in the quantity of spaghetti dinners demanded that is caused by the decrease in the price of tacos and the increase in average income?
A. When there is a change in the price of tacos, and income changes at the same time, we can't say anything for certain about either the law of demand or whether spaghetti and tacos are complements.

B. Tacos are sometimes complements with spaghetti dinners.

C. The law of demand does not hold when two goods are substitutes.