The correct answer is C. Advurtise. The correct spelling is "advertise".
A. Indefinite is an adjective that means not clearly defined or determined. B. Courteous is an adjective that means polite and considerate. D. Periphery is a noun that means the outer edge or boundary of something.
The word "advurtise" is not a real word. It is a misspelling of the word "advertise". The word "advertise" is a verb that means to make known to the public by means of an advertisement.
