For a monopoly, the socially efficient level of output occurs where marginal revenue equals marginal cost. average revenue equals marginal cost. marginal revenue equals average total cost. average revenue equals average total cost.

The correct answer is: average revenue equals marginal cost.

Explanation:

In a monopoly, the socially efficient level of output is where the average revenue is equal to marginal cost. At this level, the price paid for the product is equal to the additional cost incurred on the production of that unit of product.

But the monopolist maximizes its profit by producing at the level where the marginal revenue is equal to marginal cost. This output level is less than the socially optimal level and creates a dead weight loss.

don't use it that much

ans.

heterothermic organisms include those organisms that can switch between homeothermic (having body temperature higher than environment) and poikilothermic (having variation in internal body temperature) strategies.

some migratory birds show heterothermy as they decrease their metabolic rate during cold nights to keep their body temperature low. drop in metabolic rate allows increase in production efficiency of birds that reduces the internal body temperature to make it equal to external cold temperature during cold nights.

thus, the correct answer is 'birds allow their temperature drop in order to increase their production efficiency.'