Which process is endothermic?

A.     ${\text{C}}{{\text{H}}_4}{\text{(g)}} + {\text{2}}{{\text{O}}_2}{\text{(g)}} \to {\text{C}}{{\text{O}}_2}{\text{(g)}} + {\text{2}}{{\text{H}}_2}{\text{O(g)}}$

B.     ${\text{HCl(aq)}} + {\text{NaOH(aq)}} \to {\text{NaCl(aq)}} + {{\text{H}}_2}{\text{O(l)}}$

C.     ${\text{CaC}}{{\text{O}}_3}{\text{(s)}} \to {\text{CaO(s)}} + {\text{C}}{{\text{O}}_2}{\text{(g)}}$

D.     ${{\text{H}}_2}{\text{O(g)}} \to {{\text{H}}_2}{\text{O(l)}}$

C