The function C gives the cost, in dollars, to produce a particular product, where C (m) is the cost, in dollars, to produce m units of the product The function M dened by M (m) = C (a: + 1) C (m) gives the marginal cost, in dollars, to produce unit number a: + 1' Which of the following gives the best estimate for the marginal cost, in dollars, to produce the 57th unit of the product? C(56) T 0(57) 7 C'(56)