Aaron has a budget of $100 per month to spend on lunch. He made a table showing the total amount of lunch money he will have left after the given number of lunches. 
 Number of lunches: 0 5 10 15 
 Total amount of lunch money left ($): 100 75 50 25
 Which equation, in standard form, represents the relationship between the number of lunches, x, and the amount of lunch money Aaron will have left, y?
 A. x + 100y = 5 
 B. x + 5y = 100 
 C. 5x + y = 100 
 D. 100x + y = 5