Right answer is (c) 2CO
The explanation is: Balanced equation: 2C + O2 => 2CO [Synthesis reaction]
Oxygen is left in excess, based on the molecular weight, 24kg of carbon combines with 32kg of oxygen forming 56kg of carbon monoxide
24kg of C + 32kg of O2 => 56kg of CO
1kg of C + 4/3kg of O2 => 7/3kg of CO.