The figure shows the graph of a quadratic revenue function and a linear cost function. R(x) C(x) B Units (a) At which of the four x-values shown is the distance between the revenue and the cost greatest? O A O c OD (b) At which of the four x-values shown is the profit largest? O A O B (C) At which of the four x-values shown is the slope of the tangent to the revenue curve equal to the slope of the cost line? O A O B O D (d) what is the relationship between marginal cost and marginal revenue when profit is at its maximum value? O Pis a max when P' 0 or MR MC. O Pis a max when P or MR= MC. O Pis a max when P'= 0 or MR > MC. O Pis a max when P'= 0 or MR < MC. Dollars