Alpha is a perfectly competitive profit-maximizing firm with monthly variable cost of $4000 and monthly fixed cost of $6000. Monthly total revenue is $8000. Suppose that a portion of Alpha's fixed...

Extracted text: Alpha is a perfectly competitive profit-maximizing firm with monthly variable cost of $4000 and monthly fixed cost of $6000. Monthly total revenue is $8000. Suppose that a portion of Alpha's fixed costs are recoverable and a portion are sunk. The choices below give different possible values for the recoverable fixed costs. For which of these should Alpha shut down in the short run? (choose any and all correct answers; incorrect choices will be penalized) Select one or more: а. 3000 b. 4500 С. 6000 d. 2000