Which of the following statements is true?
(i) When a competitive firm sells an additional unit of output, its revenue increases by an amount less than the price. (ii) When a monopoly firm sells an additional unit of output, its revenue increases by an amount less than the price. (iii) Average revenue is the same as price for both competitive and monopoly firms.
a. (ii) only
b. (iii) only
c. (i) and (ii) only
d. (ii) and (iii) only