The correct sequence of passage of urea from site of production to exterior is 

Options

A. liver - blood - kidney - fat bodies -cloaca
B. liver - kidney - cloaca - blood
C. liver - blood - cloaca - ureter
D. liver - blood - kidney - ureter - cloaca

Answer

To determine the correct sequence of passage of urea from its site of production to the exterior in frogs, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Site of Urea Production**:
- Urea is produced in the liver. This is the starting point of the urea's journey.

2. **Transport of Urea to the Kidneys**:
- After its production in the liver, urea enters the bloodstream. The blood serves as the transport medium that carries urea from the liver to the kidneys.

3. **Processing in the Kidneys**:
- Once the urea reaches the kidneys, it undergoes processing. The kidneys filter the blood and prepare the urea for excretion.

4. **Movement from Kidneys to Cloaca**:
- The processed urea is then transported from the kidneys through the ureters. The ureters are tubes that carry urine from the kidneys to the cloaca.

5. **Excretion through the Cloaca**:
- Finally, the urea reaches the cloaca, which is the common exit point for excretory products. From the cloaca, urea is excreted out of the body.

### Final Sequence:
- **Liver → Blood → Kidneys → Ureters → Cloaca**

### Conclusion:
The correct sequence of passage of urea from the site of production to the exterior in frogs is: **Liver → Blood → Kidneys → Ureters → Cloaca**.

The correct answer is **Option D**.

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