Lymph

Options

A. (a) transports `CO_(2)` to lungs
B. (b) transports oxygen to brain
C. (c) returns interstitial fluid to blood
D. (d) returns RBCs and WBCs to lymph nodes

Answer

### Step-by-Step Solution:

1. **Understanding Lymph**: Lymph is a clear fluid that circulates through the lymphatic system, which is part of the immune system. It plays a crucial role in maintaining fluid balance in the body and in immune responses.

2. **Functions of Lymph**:
- **Fluid Drainage**: One of the primary functions of lymph is to drain excess fluid from the extracellular spaces in tissues and return it to the bloodstream. This helps maintain fluid balance in the body.
- **Fat Transport**: Lymph also plays a role in the absorption of fatty acids and fat-soluble vitamins from the small intestine. It transports these fats to the bloodstream, where they can be utilized by the body.
- **Immune Response**: Lymph contains lymphocytes, which are a type of white blood cell. These cells are essential for the immune response, helping to protect the body against infections and diseases.

3. **Analyzing the Options**:
- **Option A**: "Transports CO2 to lungs" - This is incorrect as lymph does not transport carbon dioxide; this is a function of the blood.
- **Option B**: "Transports oxygen to brain" - This is also incorrect; oxygen transport is primarily the function of red blood cells in the blood.
- **Option C**: "Returns interstitial fluid to blood" - This is correct. Lymph indeed returns excess interstitial fluid to the bloodstream, maintaining fluid balance.
- **Option D**: "Returns RBCs and WBCs to lymph node" - This is incorrect. While lymph does contain some white blood cells, it does not return red blood cells to lymph nodes.

4. **Conclusion**: After analyzing the options, the correct function of lymph is option C: "returns interstitial fluid to blood."