If a firm's current revenues are less than its current variable costs, it should shut downmultiple choiceif the price falls below its current fixed costs.if the marginal cost rises above marginal revenue.if expected revenues are less than expected costs.immediately.

To determine whether a firm should shut down, we need to analyze the given conditions step by step:

1. Current Revenues vs. Current Variable Costs: The question states that the firm's current revenues are less than its current variable costs. This means the firm is not covering its variable costs, which are the costs that vary with the level of output.

2. Fixed Costs: Fixed costs are costs that do not change with the level of output. If the firm is not covering its variable costs, it will also not be able to cover its fixed costs.

3. Shut Down Decision: A firm should shut down if it cannot cover its variable costs in the short run. This is because continuing to operate would result in greater losses than shutting down, as the firm would still incur fixed costs even if it stops production.

Now, let's evaluate the multiple-choice options:

a) If the price falls below its current fixed costs: This is not the correct criterion for shutting down. Fixed costs are not relevant to the shutdown decision in the short run.

b) If the marginal cost rises above marginal revenue: This condition relates to profit maximization, not the shutdown decision. A firm should produce where marginal cost equals marginal revenue, but this does not directly address the shutdown condition.

c) If expected revenues are less than expected costs: This is a broader condition that could apply to both short-run and long-run decisions. However, it is not specific to the current situation where revenues are less than variable costs.

d) Immediately: Given that the firm's current revenues are less than its current variable costs, the firm should shut down immediately to minimize losses.

Therefore, the correct answer is:

d) Immediately.