Answer:
III, IV, and V
Step-by-step explanation:
The complex [CO(NH3)6]3+ is a diamagnetic complex. It a low spin d^6 complex. Most d^6 complexes are low spin due to the higher crystal field stabilization energy of the low spin over the high spin arrangement.
d^6 metal complexes are known to be octahedral (a coordination number of 6 leads to octahedral geometry). Octahedral complexes does not have geometric isomers rather, may exist as the fac or her stereo isomers.