Ithink its the purpose of antitrust law is to support efforts of companies to take over others discourage competition in certain markets force similar companies to combine into one protect competition by preventing monopolies

The correct answer is protect competition by preventing monopolies.

A trust is a group of businesses that act like a monopoly. A monopoly is a business that controls an entire market. For example, if you could only buy a cell phone from one company, they would have a monopoly.

Monopolies can be bad for the American economy, as it decreases competition. Decreased competition gives a monopoly the chance to charge whatever they want for a product, as there is no other business that a consumer can buy it from. This is one of the many reasons why the  US has anti-trust laws.