A coordination complex compound of cobalt has the molecular formula containing five ammonia molecules, one nitro group and two chlorine atoms for one cobalt atom. One mole of this compound produces three mole ions in an aqueous solution; on reacting with excess of $\mathrm{AgNO}_{3}, \mathrm{AgCl}$ is precipitated. The ionic formula for this complex would be:

• Correct answer
  A

  $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{NO}_{2}\right)\right] \mathrm{Cl}_{2}$
• B

  $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5} \mathrm{Cl}\right]\left[\mathrm{Cl}\left(\mathrm{NO}_{2}\right)\right]$
• C

  $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4}\left(\mathrm{NO}_{2}\right) \mathrm{Cl}\right]\left[\left(\mathrm{NH}_{3}\right) \mathrm{Cl}\right]$
• D

  $\left.\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}\right]\left[\mathrm{NO}_{2}\right)_{2} \mathrm{Cl}_{2}\right]$

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