the balanced equation for the combustion reaction is
CH₄ + 2O₂ ---> CO₂ + 2H₂O
molar ratio of methane - CH₄ to O₂ is 1:2
mass of methane burned - 32.0 g
number of methane moles burned - 32.0 g / 16 g/mol = 2 mol
according to molar ratio 1 mol of methane reacts with 2 mol of oxygen
therefore 2 mol of methane reacts with 4 mol of oxygen
answer is B. 4 mol