True or False?
The statement is false. Consider the Figure below.
It should be obvious that the fact that there is only one firm producing a particular product does not mean that its average cost of production has to be below the price at which marginal cost equals marginal revenue. There is no reason why, in a particular case, the ATC curve in the Figure could not be higher. And it is not impossible, although it is unlikely, that the ATC curve in a particular case could be tangent to the demand curve. In that case, the monopoly would be just covering its average total cost, thereby earning zero excess profits. This would be the case where there is barely enough demand for the product to support a single firm---slightly less demand would make it unprofitable for any firm to produce the product.