John earns $8 per hour for his after-school job. He never works more than 18 hours in a week, and he never works a fraction of an hour. The equation that models this situation is A = 8h, where A represents the amount John earns and h represents the number of hours John works in a week. What is the reasonable domain of the function A in the given context?

A. All integers greater than or equal to 0
B. All integers less than or equal to 18
C. All integers greater than or equal to 0 and less than or equal to 18
D. All integers greater than or equal to 0 and less than or equal to 144