The graph which represents the following reaction is:

${\left({\mathrm{C}}_6{\mathrm{H}}_5\right)}_3\mathrm{C}-\mathrm{Cl}\frac{{\mathrm{OH}}^{-}}{\mathrm{Pyridine}}{\left({\mathrm{C}}_6{\mathrm{H}}_5\right)}_3\mathrm{C}-\mathrm{OH}$

Given reaction,

${\left({\mathrm{C}}_6{\mathrm{H}}_5\right)}_3\mathrm{C}-\mathrm{Cl}\frac{{\mathrm{OH}}^{-}}{\mathrm{Pyridine}}{\left({\mathrm{C}}_6{\mathrm{H}}_5\right)}_3\mathrm{C}-\mathrm{OH}$

It is $S_{\mathrm{N}}1$ reaction. So rate of reaction depends on the concentration of alkyl halide only.

So, the correct graph is option (C).