The type of unsaturation present in crotonic acid is -

Options

A. `alpha,beta`
B. `beta,alpha`
C. `alpha, alpha`
D. `beta,beta`

Explanation

To determine the type of unsaturation present in crotonic acid, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Structure of Crotonic Acid**:
- Crotonic acid is also known as 2-butenoic acid. Its molecular structure can be represented as:
\[ \text{CH}_3\text{CH}=\text{CHCOOH} \]
- This structure shows that crotonic acid has a double bond between the second and third carbon atoms.

2. **Analyze the Functional Groups**:
- In the structure, we can see that crotonic acid contains a carboxylic acid group (-COOH) at the end of the carbon chain. The presence of this functional group is important for naming and identifying the type of unsaturation.

3. **Identify the Type of Unsaturation**:
- Unsaturation in organic chemistry typically refers to the presence of double or triple bonds. In crotonic acid, the double bond between the second and third carbon atoms indicates unsaturation.
- Additionally, since the carboxylic acid group is attached to the carbon chain, we can classify the type of unsaturation as alpha, beta unsaturation. The carbon adjacent to the carboxylic acid (the second carbon) is referred to as the alpha carbon, and the next carbon (the third carbon) is referred to as the beta carbon.

4. **Conclusion**:
- Therefore, the type of unsaturation present in crotonic acid is **alpha, beta unsaturation**.

### Final Answer:
The type of unsaturation present in crotonic acid is **alpha, beta unsaturation**.