Which reaction shown is endothermic?
- A$\text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2$
- B$\text{CaO} + 2\text{HCl} \rightarrow \text{CaCl}_2 + \text{H}_2\text{O}$
- C$2\text{Ca} + \text{O}_2 \rightarrow 2\text{CaO}$
- D$\text{Ca} + 2\text{HCl} \rightarrow \text{CaCl}_2 + \text{H}_2$