4. A 'standard-case' profit-maximizing perfect competitor has the following short-run Total Cost function: TC = 2400 + 20Q + (2/3)Q2. [NOTE: If the firm shuts down in the short run, the profit-maximizing level of output Q* = 0.] Fixed Costs (FC) = $/period. The formula for Variable Costs is VC = The formula for Average Variable Costs is AVC = The formula for Marginal Cost is MC = If the market price is $100/unit, then: (a) the firm will produce Q* = units/period. (b) its profit = $/period. If the market price falls to $80/unit, then: (c) it will produce Q* = units/period. (d) its profit =_ $/period