A monopolist has identified two market segments with demand functions: D1(y1) = 10 - y1 and D2(y2) = 20 - y2. What are the marginal revenue functions for each of these two segments? Choose the correct option:
a) MR1(y1) = 10 - 2y1 b) MR1(y1) = 10 - y1 c) MR2(y2) = 20 - 2y2 d) MR2(y2) = 20 - y2
