Which of the following statements is not true about the complex ion [CrCl(NO2)(en)2]+ ?
a. It has two geometrical isomers *cis* and *trans*
b. *cis* and *trans* forms are not diastereomers to each other
c. Only the *cis* isomer displays optical activity
d. It has three optically active isomers: *d*, *l* and *trans* forms