The number of stereoisomers is maximum for

A

$$[\text{Co(en)}_3]^{3+}$$

B

$$[\text{Co(en)}_2\text{ClBr}]^+$$

C

$$[\text{Co(NH}_3)_4\text{Cl}_2]^+$$

D

$$[\text{Co(NH}_3)_4\text{ClBr}]^+$$