Baseball fans can buy tickets for seats in the lower deck or upper deck of the stadium. Tickets for the lower deck cost $42 each. Tickets prices for the upper deck are 75% of the cost of tickets for the lower deck. Which inequality represents all possible combinations of x, the number of tickets for the lower deck, and y the number of tickets for the upper deck, that someone can buy for no more than $800?
A.) 42x + 56y < 800
B.) 42x + 56y > 800
C.) 42x + 31.5y > 800
D.) 42x + 31.5y < 800