A model of demand predicts that a rise in price will cause a decrease in the quantity of a good consumers want to buy anda in price will cause an increase in the quantity of a good consumers want to buy. In this model: decrease a. the cause is the change in the price and the effect is a change in the quantity of the good consumers want to purchase. b. the cause is the change in the price and the effect is a change in the quality of the good consumers want to purchase. c. the cause is the change in the product quality and the effect is a change in the quantity of the good consumers want to purchase d. the cause is the change in the quantity of the good consumers want to purchase and the effect is a change in the price