In this paragraph, some statements are given based on isomerism. Read the following statements given for every question and provide the answer.
Which of the following cyclic dienes does not show geometrical isomerism?

Options

A.
B.
C.
D.

Answer

To determine which cyclic diene does not show geometrical isomerism, we need to analyze the structures of the cyclic dienes provided in the options. Geometrical isomerism, also known as cis-trans isomerism, occurs when there is restricted rotation around a double bond, and the substituents attached to the double-bonded carbons can be arranged in different spatial configurations.

### Step-by-Step Solution:

1. **Understand Geometrical Isomerism**:
- Geometrical isomerism occurs due to the presence of double bonds or rings that restrict rotation. In cyclic compounds, if there are two different substituents on the same carbon atoms involved in a double bond, cis and trans forms can exist.

2. **Analyze Each Option**:
- Let's denote the cyclic dienes as A, B, C, and D.
- For each structure, check if there are two different groups attached to the double-bonded carbons.

3. **Evaluate Option A**:
- If option A has two different groups on the double-bonded carbons, it can show geometrical isomerism (cis and trans forms).

4. **Evaluate Option B**:
- Similarly, if option B has two different groups on the double-bonded carbons, it can also show geometrical isomerism.

5. **Evaluate Option C**:
- For option C, if there are two identical groups on one of the double-bonded carbons (e.g., two methyl groups), it cannot show geometrical isomerism because there are no different substituents to create cis and trans forms.

6. **Evaluate Option D**:
- If option D has a complete valency on the double-bonded carbons (for example, if both carbons are attached to the same groups and no hydrogens), it will not show geometrical isomerism due to lack of different substituents.

7. **Conclusion**:
- After analyzing all options, if option D has no possibility of forming cis and trans isomers due to complete valency or identical substituents, then option D is the correct answer.

### Final Answer:
**Option D does not show geometrical isomerism.**