To raise money, a school band is selling tickets to a breakfast. The graph on the coordinate grid below shows the functional relationship between the number of tickets sold and the revenue.

The graph shows revenue in dollars on vertical axis and number of tickets sold on horizontal axis. A segment from (0, 0) to (80, 400).

What is the domain of the function?

A.
integers from 0 to 400

B.
real numbers from 0 to 500

C.
integers from 0 to 80

D.
real numbers from 0 to 100