Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: The total number of geometrical isomers shown by $[Co(en)_2 Cl_2]^{+}$ complex ion is three.
Reason $R$: $[Co(en)_2 Cl_2]^{+}$ complex ion has an octahedral geometry.
In the light of the above statements,choose the most appropriate answer from the options given below:

• A
  Both $A$ and $R$ are correct and $R$ is the correct explanation of $A$.
• B
  $A$ is correct but $R$ is not correct.
• C
  $A$ is not correct but $R$ is correct.
• D
  Both $A$ and $R$ are correct but $R$ is not the correct explanation of $A$.