The molecular formula of a cobalt coordination complex contains five ammonia molecules,one nitro group,and two chlorine atoms for one cobalt atom. In an aqueous solution,one mole of the substance produces $3$ moles of ions. Upon reacting this solution with an excess of silver nitrate solution,$2$ moles of $AgCl$ precipitate are obtained. What is the ionic formula of the complex?

• A
  $[Co(NH_3)_4(NO_2)Cl] \cdot (NH_3)Cl$
• B
  $[Co(NH_3)_5Cl] \cdot Cl(NO_2)$
• C
  $[Co(NH_3)_5(NO_2)]Cl_2$
• D
  $[Co(NH_3)_5(NO_2)_2]Cl_2$