Which of the following compound show optical isomerism?

Options

A. cis-`[CrCl_(3)(NHl_(3))_(3)]`
B. cis-`[Co(NH_(3))_(4)Cl_(2)]^(+)`
C. `[Co(en)_(3)]^(3+)`
D. trans-`[Co(en)_(2)Cl_(2)]^(+)`

Explanation

To determine which of the given compounds shows optical isomerism, we need to analyze the structures of each compound and check for the presence of a plane of symmetry. A compound exhibits optical isomerism if it lacks a plane of symmetry, meaning it cannot be superimposed on its mirror image.

### Step-by-Step Solution:

1. **Identify the Compounds**:
The question provides four coordination compounds. We will analyze each one for optical isomerism.

2. **Analyze the First Compound: CrCl3(NH3)3**:
- Structure: Chromium is the central metal ion surrounded by three chloride ions and three ammonia molecules.
- Symmetry: This compound has a plane of symmetry due to the arrangement of ligands. Therefore, it does not show optical isomerism.

3. **Analyze the Second Compound: Co(NH3)4Cl2**:
- Structure: Cobalt is the central metal ion with four ammonia ligands and two chloride ions.
- Symmetry: This complex also has a plane of symmetry, which means it does not exhibit optical isomerism.

4. **Analyze the Third Compound: Co(en)3**:
- Structure: Cobalt is the central metal ion surrounded by three bidentate ethylenediamine (en) ligands.
- Symmetry: This compound lacks a plane of symmetry because the arrangement of the bidentate ligands does not allow for any symmetry plane. Thus, it can show optical isomerism.

5. **Analyze the Fourth Compound: trans-Co(en)2Cl2+**:
- Structure: Cobalt is the central metal ion with two bidentate ethylenediamine ligands and two chloride ions in a trans configuration.
- Symmetry: In this case, the trans arrangement leads to the presence of a plane of symmetry. Therefore, it does not exhibit optical isomerism.

6. **Conclusion**:
Among the given compounds, only Co(en)3 shows optical isomerism because it does not possess a plane of symmetry.

### Final Answer:
The compound that shows optical isomerism is **Co(en)3**.