8. (The Short-Run Firm Supply Curve) Each of the following situations could exist for a perfectly competitive firm in the short run. In each case, indicate whether the firm should produce in the short run or shut down in the short run, or whether additional information is needed to deter- mine what it should do in the short run. a. Total cost exceeds total revenue at all output levels. b. Variable cost exceeds total revenue at all output levels. C. Total revenue exceeds fixed cost at all output levels. d. Marginal revenue exceeds marginal cost at the current output level. e. Price exceeds average total cost at all output levels. f. Average variable cost exceeds price at all output levels. g. Average total cost exceeds price at all output levels