Suppose the demand curve for a business firm is downward sloping. Which statement is true about elasticity (ED), marginal revenue (MR), and/or total revenue (TR)?
a. In the elastic range of the demand curve, MR > 0 when selling price is reduced.
b. TR is constant along the length of the demand curve.
c. MR = selling price when the demand curve is downward sloping.
d. ED < 1 during the elastic range of the demand curve.