Which of the following expressions is correct to calculate enthalpy of a reaction ?
A. `DeltaH_("reaction")=SigmaDelta_(f)H_("reactions")-SigmaDelta_(f)H_("products")`
B. `DeltaH_("reaction")=SigmaB.E._("products")-Sigma B.E._("reactants")`
C. `DeltaH_("reaction")=SigmaB.E._("reactants")-SigmaB.E._("products")`
D. `DeltaH_("reaction")=DeltaH_(1)xxDeltaH_(2)xxDeltaH_(3)...`
