Answer: A firm will shut down in the short run if "d. total revenue is less than total variable cost".
Explanation: The critically low market price at which your income is exactly equal to the variable cost (or, in other words, at which the losses are exactly equal to the fixed costs) is called the closing point. At prices above the closing point, the company will produce along its marginal cost curve, because even if it lost money, it would lose more closing. At prices below the closing point, it will produce nothing because closing will only lose its fixed costs.
