The loop of Henle is associated with:

Options

A. kidney
B. brain
C. liver
D. ileum

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the association of the loop of Henle with specific organs: kidney, brain, liver, or ileum.

2. **Identifying the Loop of Henle**: The loop of Henle is a U-shaped structure that is part of the nephron, which is the functional unit of the kidney.

3. **Function of the Loop of Henle**: The loop of Henle plays a crucial role in the concentration of urine by creating a concentration gradient in the medulla of the kidney, which is essential for water reabsorption.

4. **Analyzing the Options**:
- **Kidney**: The loop of Henle is found in the nephron, which is located in the kidney.
- **Brain**: The brain is associated with neurons, not the loop of Henle.
- **Liver**: The liver does not contain the loop of Henle.
- **Ileum**: The ileum is part of the small intestine and does not contain the loop of Henle.

5. **Conclusion**: Since the loop of Henle is part of the nephron and the nephron is the functional unit of the kidney, the correct answer is **kidney** (option A).

**Final Answer**: The loop of Henle is associated with the **kidney**.

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