The unsaturated fatty acid essential of human being but not to other animals is

Options

A. Oleic acid
B. linoleic acid
C. Linolenic acid
D. Arachidonic acid

Answer

To solve the question regarding the unsaturated fatty acid that is essential for human beings but not for other animals, we will analyze the options provided and determine which one fits the criteria.

### Step-by-Step Solution:

1. **Understanding Unsaturated Fatty Acids**:
- Unsaturated fatty acids are those that contain one or more double bonds in their hydrocarbon chain. They are classified into monounsaturated and polyunsaturated fatty acids.

2. **Identifying Essential Fatty Acids**:
- Essential fatty acids are those that the body cannot synthesize and must be obtained through diet. In humans, the essential fatty acids include omega-3 and omega-6 fatty acids.

3. **Analyzing the Options**:
- **Option 1: Oleic Acid**:
- Oleic acid is a monounsaturated omega-9 fatty acid. It is not considered essential because the body can synthesize it.
- **Option 2: Linoleic Acid**:
- Linoleic acid is a polyunsaturated omega-6 fatty acid. It is essential for both humans and many animals, serving as a precursor for other important compounds.
- **Option 3: Alpha-Linolenic Acid**:
- Alpha-linolenic acid is an omega-3 fatty acid. It is essential for humans but is also required by some animals.
- **Option 4: Arachidonic Acid**:
- Arachidonic acid is a polyunsaturated omega-6 fatty acid that is essential for humans but can be synthesized by many animals from linoleic acid.

4. **Conclusion**:
- The correct answer is **Arachidonic Acid** (Option 4), as it is an unsaturated fatty acid that is essential for human beings but not required by many other animals.

### Final Answer:
The unsaturated fatty acid essential for human beings but not to other animals is **Arachidonic Acid**.