consider the market for arugula, a normal good. which of the following changes would result in an increase in both the equilibrium price and the equilibrium quantity of arugula?
a. A decrease in consumer income
b. An increase in the price of salad dressing, a complement I consumption
c. A decrease in the price of radicchio, a substitute in consumption
d. An increase in the price of water irrigation for arugula farms
e. An increase in population