A concert hall sells show tickets for $12 each and has a capacity of 400 people. The function M(x) = 12x represents the amount of money the concert hall makes from ticket sales, where x is the number of people in the audience. What would be the most appropriate domain for the function? (1 point)
All real numbers
All whole numbers
Whole numbers that are multiples of 12
Whole numbers less than or equal to 400