Octane (C8H18) is burned with 80% stoichiometric air, resulting in incomplete combustion with CO and 4 moles

Question:

Octane (C8H18) is burned with 80% stoichiometric air, resulting in incomplete combustion with CO and 4 moles of unburned carbon being the only additional components in the products. The number of moles of CO2 in the products of combustion is:
(A) 2.2
(B) 2.8
(C) 3.4
(D) 3.6