I would say it’s B because at the end we always have to look at the products not the reactants, and since they already balanced the equation then there are 2 Carbons. Hope you’d get it right :))
Consider the following reaction at equilibrium. 2co2 (g) 2co (g) + o2 (g) h° = -514 kj le châtelier's principle predicts that the equilibrium partial pressure of co (g) can be maximized by carrying out the reaction a. at high temperature and high pressure b. at high temperature and low pressure c. at low temperature and low pressure d. at low temperature and high pressure e. in the presence of solid carbon