A local daycare has a daily operating cost of $900 plus a cost of $250 per child that attend. If a parent pays $420 per child, which inequality could be used to determine the number of children, c, they must accept to make money and become profitable?

a. 450c < 900+ 250c
b. 250c > 900+450c
c. 450c > 900 + 250c
d. 250c < 900 + 450c