Mildred and Robert are the only buyers in the market for DVDs.
Mildred buys 12 DVD's when the price of a DVD is $9, 9 DVD's when the price of a DVD Is $11, and 8 DVDs a month when the price of a DVD is $15.
Robert buys 18 DVDs a month when the price of a DVD is $9, 6 DVDs when the price of a DVD is $11, and zero when the price of a DVD is $15.
In the market for DVDs the quantity demand ______
a. increases as the price rises
b. increases as the price falls
c. at $11 a DVD is 6 DVDs a month
d. at $9 a DVD is less than the quantity demanded at $11 a DVD
e. at $11 a DVD is 9 DVDs a month