C because 0.25 is the amount needed in one serving. 2 liters is the amount that you have. How many servings can you make from that? 8 because you divide 0.25 into 2.
B because 0.25 is the amount in a serving. Multiplying by s will get you the amount of servings in 2 liters. s = 8 0.25*8=2