Isomorphism of simple graphs is an equivalence relation.
Any graph is Isomorphic to itself so Reflexive.
If $\text{G}$ Isomorphic to $\text{H}$ then $\text{H}$ Isomorphic to $\text{G}$ so Symmetric. And if $\text{G}$ Isomorphic to $\text{H}$ and $\text{H}$ Isomorphic to $\text{I}$ then $\text{G}$ Isomorphic to $\text{I},$ so transitive.
So, isomorphism of simple graphs is an equivalence relation.
There will be $17$ equivalence classes for $\text{R}.$
The equivalence class will be $\text{K1}$ to $\text{K10}$ and $\text{C4}$ to $\text{C10}.$ Note that $\text{C3}$ is in same equivalence class of $\text{K3}.$