Which of the following accurately describes the function of the muscular system?
O A. To prevent and fight disease
B. To provide support for the body
C. To get rid of wastes and excess water
D. To allow the body to move​

I believe it is D, but I may be mistaken. Could be B

We calculate for the number of moles of water given its mass by dividing the given mass by the molar mass. 
                               n water = (36.04 g) / (18 g/mol) 
                                n water = 2 mols
From the given balanced equation, every 6 moles of water produced will require 7 moles of oxygen.
                                n oxygen = (2 mols H2O) x (7 moles O2 / 6 moles H2O)
                                n oxygen  = 2.33 mols O2