For a firm whose total cost and total revenue functions are given by: TC = mQ + c, TR = Po.Q which of the following statements is true? (m is the per unit cost, c the fixed costs and Po the market price) a. If variable costs per unit (m) increase, the break even point (Q) will fall. b. If fixed costs (c) rise, the break even point will be unchanged. c. If fixed costs (c) fall, the break even point will fall. d. If market price (PO) rises, the break even point will rise.