a. For quantities between 40 000 and 50 000 the demand curve is elastic because increases in the price over this range will cause revenue to increase. b. For quantities between 35 000 and 40 000 the demand curve is inelastic because increases in the price over this range will cause revenue to increase. c. For quantities between 10 000 and 15 000 the demand curve is elastic because decreases in the price over this range will cause revenue to decrease. d. For quantities between 5 000 and 10 000 the demand curve is unitary elastic because decreases in the price over this range will not cause any change in revenue