Choose the reaction(s) from the following options, for which the standard enthalpy of reaction is equal to the standard enthalpy of formation.

A

$$2H_2(g) + O_2(g) \rightarrow 2H_2O (l)$$

B

$$2C(g) + 3H_2(g) \rightarrow C_2H_6(g)$$

C

$$\frac{3}{2} O_2(g) \rightarrow O_3(g)$$

D

$$\frac{1}{8}S_8(s) + O_2 (g) \rightarrow SO_2(g)$$