cnh2n+2 + o2

Correct option is C. $$\left ( \dfrac{3n+1}{2} \right )O_{2}$$
Reaction for complete combustion of $$\mathrm{C_nH_{2n+2}}$$:

$$\mathrm{C_nH_{2n+2} + (\cfrac{3n+1}{2})O_2 \rightarrow nCO_2 + (n+1)H_2O}$$

Therefore, in the complete combustion of $$\mathrm{C_nH_{2n+2}}$$, the no. of moles of oxygen required are $$\cfrac{3n+1}{2}$$

Hence, Option "C" is the correct answer.