Which of the following can exhibit optical isomerism:
(i)`[Cr(gly)_3]^0`
(ii) `[CoBr_(2)CI_(2)(SCN)_(2)]^(3-)`
(iii) `[Co(en)_(3)]^(3+)`
(iv) `Na[PtBrCI(NO_(2))(NH_(3))]`

Options

A. (i), (ii) only
B. (i), (ii), (iii)
C. (ii), (iv) only
D. (i), (iii) only

Explanation

To determine which of the given complexes can exhibit optical isomerism, we need to analyze each complex based on its structure and symmetry.

### Step-by-Step Solution:

1. **Understanding Optical Isomerism**:
- Optical isomerism occurs in compounds that can rotate plane-polarized light. These compounds are chiral and do not have a plane of symmetry.

2. **Analyzing Complex (i) `[Cr(gly)_3]^0`**:
- Glycine (gly) acts as a bidentate ligand, meaning it coordinates to the chromium ion at two sites.
- The structure of `[Cr(gly)_3]` will be octahedral with three bidentate ligands.
- This complex can exist in two non-superimposable mirror images (dextrorotatory and levorotatory forms).
- **Conclusion**: This complex exhibits optical isomerism.

3. **Analyzing Complex (ii) `[CoBr_(2)Cl_(2)(SCN)_(2)]^(3-)`**:
- This complex has six monodentate ligands (2 Br, 2 Cl, and 2 SCN).
- The arrangement of these ligands can lead to a symmetrical octahedral structure.
- Since it has a plane of symmetry, it cannot exist as chiral.
- **Conclusion**: This complex does not exhibit optical isomerism.

4. **Analyzing Complex (iii) `[Co(en)_(3)]^(3+)`**:
- Ethylenediamine (en) is also a bidentate ligand.
- The complex consists of three bidentate ligands, resulting in an octahedral geometry.
- Similar to the first complex, this can also exist in two non-superimposable mirror images.
- **Conclusion**: This complex exhibits optical isomerism.

5. **Analyzing Complex (iv) `Na[PtBrCl(NO_(2))(NH_(3))]`**:
- This complex has four different ligands (Br, Cl, NO2, NH3) and is square planar.
- A square planar complex can have a plane of symmetry, which means it is not chiral.
- **Conclusion**: This complex does not exhibit optical isomerism.

### Final Answer:
The complexes that exhibit optical isomerism are:
- (i) `[Cr(gly)_3]^0`
- (iii) `[Co(en)_(3)]^(3+)`