Which is useful in human beings

Options

A. Cholesterol
B. Animal fat
C. High density lipoprotein cholesterol
D. Low density lipoprotein cholesterol.

Answer

To answer the question "Which is useful in human beings?" regarding cholesterol and lipoproteins, we can break down the information as follows:

### Step-by-Step Solution:

1. **Understanding Cholesterol and Lipoproteins**:
- Cholesterol is a type of fat found in the blood, and it is essential for various bodily functions, including the formation of cell membranes and hormones.
- Lipoproteins are molecules that transport cholesterol in the bloodstream. The two main types of lipoproteins are Low-Density Lipoprotein (LDL) and High-Density Lipoprotein (HDL).

2. **Identifying LDL and HDL**:
- **Low-Density Lipoprotein (LDL)**: Often referred to as "bad cholesterol." High levels of LDL can lead to plaque buildup in arteries, increasing the risk of heart disease and stroke.
- **High-Density Lipoprotein (HDL)**: Known as "good cholesterol." HDL helps remove cholesterol from the bloodstream and transport it to the liver for excretion. Higher levels of HDL are associated with a lower risk of heart disease.

3. **Evaluating the Options**:
- The question provides several options: cholesterol, animal fat, high-density lipoprotein, low-density lipoprotein, and cholesterol again.
- Among these, HDL (high-density lipoprotein) is recognized as beneficial for human health.

4. **Conclusion**:
- Based on the information, the most useful option in human beings is **High-Density Lipoprotein (HDL)** cholesterol, as it plays a protective role in cardiovascular health.

### Final Answer:
The correct answer is **High-Density Lipoprotein (HDL) cholesterol**.