To maximize their profits and defend those profits from competitors, monopolistically competitive firms must
a. lobby government to erect barriers to entry in their industries.
b. achieve economies of scale.
c. limit foreign competition in their markets by encouraging the government to impose tariffs and other trade restrictions.
d. differentiate their products.

The correct answer is D. differentiate their products.

Explanation:

Product differentiation is a competitive strategy that aims at the consumer perceiving differently the product or service offered by a company, with respect to those of the competition.

Product differentiation can be based mainly on various attributes such as quality, color, size, after-sales service, specialized attention, location, brand recognition or luxury. But any attribute makes perceive a product or service differently is considered product differentiation.

It should be noted that the differentiation also has a subjective element since consumers can perceive that a certain brand is different from another based not on the comparison of objective characteristics but on the idea that they have made of the company and its image.

1. avoid them

2. a talk with them

3. ask someone you trust

4. ignore

5. call police