Combustion of ethanol takes place according to the following unbalanced equation.

___ ${{\text{C}}_{\text{2}}}{{\text{H}}_{\text{5}}}{\text{OH(l)}} +$ ___ ${{\text{O}}_{\text{2}}}{\text{(g)}} \to$ ___ ${\text{C}}{{\text{O}}_{\text{2}}}{\text{(g)}} +$ ___ ${{\text{H}}_{\text{2}}}{\text{O(l)}}$

What is the mole ratio of ethanol to oxygen in the balanced equation?

A.     1:1

B.     2:1

C.     1:3

D.     2:7

C