Given below are two statements, one is labelled as assertion $\mathbf{A}$ and the other is labelled as Reason $\mathbf{R}$.
assertion $\mathbf{A}$ : ${\left[\mathrm{CoCl}{\left({\mathrm{NH}}_3\right)}_5\right]}^{2+}$ absorbs at lower wavelength of light with respect to ${\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_5\left({\mathrm{H}}_2\mathrm{O}\right)\right]}^{3+}$
Reason $\mathbf{R}$: It is because the wavelenght of light absorbed depends on the oxidation state of the metal ion.
In the light of the above statements,choose the correct answer from the options given below:

• Correct answer
  A

  $\mathbf{A}$ is false but $\mathbf{R}$ is true
• B

  $\mathbf{A}$ is true but $\mathbf{R}$ is false
• C

  Both $\mathbf{A}$ and $\mathbf{R}$ are true and $\mathbf{R}$ is the correct explaination of $\mathbf{A}$ 
• D

  Both $\mathbf{A}$ and $\mathbf{R}$ are true and $\mathbf{R}$ is NOT the correct explaination of $\mathbf{A}$ 

Hence, the correct answer is option: 'A'.