Which chemical equation is balanced to show that mass is conserved during the reaction?

Question

A.Na+Cl -> NaCl
B.2H2 O2 -> CO2+2H2 O + O2
C.CH4+O2 -> CO2+2H2 O
D.AgNO3+MgCl2 -> AgCl+MgNO3

Answer 1

C. CH4 + 2O2 -> CO2 + 2H2O