Which of the following. Options about sites of digestion is CORRECT ?

Options

A.
B.
C.
D.

Answer

To solve the question regarding the correct statements about the sites of digestion, we will analyze the digestion processes of carbohydrates, proteins, fats, and nucleic acids step by step.

### Step-by-Step Solution:

1. **Digestion of Carbohydrates:**
- Carbohydrate digestion begins in the **mouth** where salivary amylase (an enzyme) starts breaking down starches into simpler sugars.
- It continues in the **small intestine**, where pancreatic amylase further breaks down carbohydrates into monosaccharides like glucose.
- **Conclusion:** Carbohydrate digestion occurs in both the mouth and small intestine.

2. **Digestion of Proteins:**
- Protein digestion starts in the **stomach** with the action of pepsin, an enzyme that breaks down proteins into smaller peptides.
- It is completed in the **small intestine**, where enzymes like trypsin and chymotrypsin further digest peptides into amino acids.
- **Conclusion:** Protein digestion does not start in the mouth; it starts in the stomach.

3. **Digestion of Fats:**
- Fat digestion does not begin in the mouth or stomach. Instead, it primarily occurs in the **small intestine** where bile salts emulsify fats and pancreatic lipase breaks them down into fatty acids and glycerol.
- **Conclusion:** There is no digestion of fats in the mouth or stomach.

4. **Digestion of Nucleic Acids:**
- Nucleic acids (DNA and RNA) begin their digestion in the **stomach** and are further broken down in the **small intestine** by nucleases.
- **Conclusion:** Nucleic acid digestion starts in the stomach, not just in the small intestine.

### Final Answer:
The only correct statement regarding the sites of digestion is that **carbohydrate digestion starts in the mouth and continues in the small intestine**.