In which equation is the enthalpy change correctly identified as an enthalpy change of formation?
- A$\text{C(g)} + \text{O}_2\text{(g)} \rightarrow \text{CO}_2\text{(g)}$
- B$\text{C(s)} + \frac{1}{2}\text{O}_2\text{(g)} \rightarrow \text{CO(g)}$
- C$2\text{N(g)} + 4\text{O(g)} \rightarrow \text{N}_2\text{O}_4\text{(g)}$
- D$2\text{NO(g)} + \text{O}_2\text{(g)} \rightarrow 2\text{NO}_2\text{(g)}$