Autility (such as a power company) which controls all services in a designated area is called a

These are the choices I found on the internet:
A)trust.
B)cartel.
C)natural monopoly.
D)devised oligopoly.

The best answer would be letter C - natural monopoly. This is a situation where one firm can supply a market's entire demand (because of a unique raw material, technology, or other factors) for a good or service at a value lower than two or more firms.