Statement (A):   ${\text{C}}_{\text{(s)}}+{\text{O}}_{\text{2(g)}}\to {\text{CO}}_{\text{2(g)}}$follow law of chemical combination.

Statement (B): ${\text{CaCO}}_{\text{3(s)}}\stackrel{\Delta }{\to }{\text{CaO}}_{\text{(s)}}+{\text{CO}}_{\text{2(g)}}$ follow law of chemical decomposition.

 Statement (C): ${\text{NaOH}}_{\text{(aq)}}+\text{HC}{l}_{\text{(aq)}}\to \text{NaC}{l}_{\text{(aq)}}+{\text{H}}_{\text{2}}{\text{O}}_{\left(l\right)}$ follow law of chemical displacement.

Two (or) more reactant combine to give single product that is combination reaction.

${\text{C}}_{\text{(s)}}+{\text{O}}_{\text{2(g)}}\to {\text{CO}}_{\text{2(g)}}$ Follow law of chemical combination.

One reactant broken down into simpler substances is called law of decomposition.

${\text{CaCO}}_{\text{3(s)}}\stackrel{\Delta }{\to }{\text{CaO}}_{\text{(s)}}+{\text{CO}}_{\text{2(g)}}$ Follow law of chemical decomposition.

 ${\text{NaOH}}_{\text{(aq)}}+\text{HC}{l}_{\text{(aq)}}\to \text{NaC}{l}_{\text{(aq)}}+{\text{H}}_{\text{2}}{\text{O}}_{\left(l\right)}$ it’s a chemical double displacement (or) neutralization               reaction.