Toothbrushes sold by firms in monopolistic competition because a. are not; a small number of firms compete b. are; a large number of firms make an identical product c. are not; many firms produce differentiated toothbrushes and entry into the market is easy d. are; many firms produce differentiated toothbrushes and entry into the market is easy.

D. are; many firms produce differentiated toothbrushes and entry into the market is easy.

Explanation:

What is Monopolistic Competition?

These are industries that compete on producing or offering products and services which are similar but can not be an excellent substitute of the other.

Entering into this kind of business has low barriers because what the other competitors decide doesn't have an impact on the other own in a direct way.

Main characteristics of monopolistic competition:

Industries offer similar but not identical products for example cleaning detergents are similar but not identical.

They differ from monopoly by the fact that in the monopolistic competition firms have less power in raising their product prices with an aim to make more profit.

The power they have is to differentiate their product from the rest in order to make more money from it and have more customers such as some toothbrush are now electrical which allows them to clean teeth differently than the manual ones.

The differentiation is hard also considering that these similar products are used for the same thing , like toothbrush are all for brushing teeth so the question is how the firm make their look exceptional to the other toothbrush that does the same thing.

The variation in prices also make it even complicated for customers to say that if they are expensive they work more efficiently, the uncertainty affect the business.

is there a year set? the question is incomplete

yes he did writing dots to make the answer