Number of molecules of water in 6 moles

I mol of anything is 6.02 * 10^23 (in this case molecules of water)
6 mols of water = x

1/6 = 6.02 * 10^23 / x Cross multiply
x = 6 * 6.02* 10^23
x = 3.612 * 10^24 molecules in 6 mols of water

Most likely a is the answer - because  you generate   38 atp's but also consume an atp.   each atp gives approx. less than 4 kcal so probably a is the closest answer.