[A] : Gall stones are pebbie sized structures that formed in the gall bladder.
[R]: Gall stones develop when excess cholesterol in the bile precipitates out of solution, trapping calcium and bile salts.

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

To solve the question regarding gallstones, we will break down the information provided in the assertion and reason statements step by step.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that gallstones are pebble-sized structures that form in the gallbladder.
- This is a true statement as gallstones indeed are small, hard deposits that can develop in the gallbladder.

2. **Understanding the Reason**:
- The reason states that gallstones develop when excess cholesterol in the bile precipitates out of solution, trapping calcium and bile salts.
- This is also a true statement. Gallstones, particularly cholesterol stones, form when there is an imbalance in the substances that make up bile.

3. **Formation of Bile**:
- Bile is produced in the liver and is composed of water, electrolytes, bile acids, cholesterol, phospholipids, and bilirubin.
- When there is too much cholesterol and not enough bile salts in the bile, the cholesterol can crystallize and form stones.

4. **Classification of Gallstones**:
- Gallstones are classified based on their chemical composition into three types: cholesterol stones, pigment stones, and calcium stones.
- Cholesterol stones form when there is an excess of cholesterol in the bile, leading to its precipitation.

5. **Conclusion**:
- Both the assertion and reason are true. The reason provides a correct explanation for the assertion.
- Therefore, the correct answer to the question is that both the assertion and reason are true, and the reason correctly explains the assertion.

### Final Answer:
Both the assertion and reason are true, and the reason is the correct explanation of the assertion.

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