A perfectly competitive firm maximizes profits​ (or minimize​ losses) when it produces the ...

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A perfectly competitive firm maximizes its profit when it produce that level of output at which marginal revenue equals marginal cost.

Since, a perfectly competitive firm is a price taker, its marginal revenue is always equal to price. So, at profit-maximizing level of output, price always equals marginal cost for a perfectly competitive firm.

However, price shold be greater than variable cost other wise firm will shut down or would not operate in short-run.

Price can be less than average total cost in the short-run, provided it is greater than average variable cost. In such scenario firm will operate.

Hence, the correct answer is option (D).