Which of these is a balanced chemical equation?

A. CO(g) + 2O2(g) → 2CO2(g)
B. 2CO(g) + O2(g) → 2CO2(g)
C. CO(g) + O2(g) → CO2(g)
D. 2CO(g) + 2O2(g) → 2CO2(g)

D. 2CO(g) + 2O2(g) → 2CO2(g)

Which of these is a balanced chemical equation?

A. H2O + CO2 → H2CO3
B. 2H2O + 2CO2 → H4CO4
C. 3H2O + 2CO2 → 2H2CO3

C. 3H2O + 2CO2 → 2H2CO3