Which of following act as middleman?

Options

A. WBC
B. Lymph
C. Plasma
D. Blood

Answer

To solve the question "Which of the following act as middleman?" we need to analyze the given options and understand their roles in the circulatory system.

### Step-by-Step Solution:

1. **Identify the Options**: The options provided are:
- A) WBC (White Blood Cells)
- B) Lymph
- C) Plasma
- D) Blood

2. **Understand the Role of Each Option**:
- **WBC**: These are involved in the immune response and do not act as a middleman in the transport of substances.
- **Lymph**: This is a fluid that is part of the lymphatic system, which collects interstitial fluid from tissues and returns it to the bloodstream. It plays a crucial role in the exchange of nutrients and waste between blood and tissues.
- **Plasma**: This is the liquid component of blood that carries cells, nutrients, hormones, and waste products but does not act as a middleman in the same way lymph does.
- **Blood**: This is the overall transport medium in the circulatory system but does not specifically act as a middleman for nutrient exchange.

3. **Analyze the Function of Lymph**:
- Lymph collects the interstitial fluid that has moved out of the blood capillaries and returns it to the bloodstream. This process is essential for maintaining fluid balance and facilitating the exchange of substances between blood and tissues.

4. **Conclusion**: Based on the analysis, lymph is the only option that acts as a middleman in the circulatory process, facilitating the exchange of nutrients and waste between blood and tissues.

### Final Answer:
The correct answer is **B) Lymph**.

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