Which of the following complexes show linkage isomerism?
(a) Co(NH3)5(NO2)2+
(b)[Co(H2O)5CO]3+
(c) [Cr(NH3)5SCN]2+
(d)[Fe(en)2Cl2]+

Choose the correct option
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, c)