Which of the following correctly explains the absorption of amino acids?

Options

A. Amino acids are mostly absorbed into the blood by active absorption. Small amounts of amino acids are generally absorbed by simple diffusion. Some amino acids are generally absorbed by simple diffusion. Some amino acids are absorbed by facilitated transport.
B. Amino acids are mostly absorbed into the blood by active absorption. Small amounts of amino acids are generally absorbed by facilitated transport. Some amino acid are absorbed by simple diffusion.
C. Amino acids are mostly absorbed into the blood by simple diffusion. Small amounts of amino acids are generally absorbed by active transport. Some amino acids are absorbed by facilitated transport.
D. Amino acids are mostly absorbed into the blood by facilitated transport. Small amounts of amino acids are generally absorbed by active absorption. Some amino acids are absorbed by simple diffusion.

Answer

To determine which statement correctly explains the absorption of amino acids, we will analyze each option step by step.

### Step 1: Understanding Amino Acid Absorption
Amino acids are primarily absorbed in the small intestine, specifically in the jejunum and ileum. The absorption mechanisms include active transport, facilitated diffusion, and simple diffusion.

### Step 2: Analyzing Each Statement
1. **First Statement**:
- "Amino acids are mostly absorbed into the blood by active absorption. Small amounts of amino acids are generally absorbed by simple diffusion. Some amino acids are generally absorbed by simple diffusion."
- This statement is mostly correct. Active transport is the primary method for amino acid absorption, and small amounts can be absorbed through simple diffusion.

2. **Second Statement**:
- "Amino acids are mostly absorbed into the blood by active absorption. Small amounts of amino acids are generally absorbed by facilitated transport. Some amino acids are absorbed by simple diffusion."
- This statement is partially correct. While it mentions active absorption, it incorrectly states that small amounts are absorbed by facilitated transport instead of simple diffusion.

3. **Third Statement**:
- "Amino acids are mostly absorbed into the blood by simple diffusion. Small amounts of amino acids are generally absorbed by active transport. Some amino acids are absorbed by facilitated transport."
- This statement is incorrect. It incorrectly states that the primary method of absorption is simple diffusion, which is not true.

4. **Fourth Statement**:
- "Amino acids are mostly absorbed into the blood by facilitated transport. Small amounts of amino acids are generally absorbed by active absorption and some amino acids are absorbed by simple diffusion."
- This statement is also incorrect. It misrepresents the primary absorption method as facilitated transport.

### Step 3: Conclusion
Based on the analysis, the first statement is the most accurate as it correctly identifies active absorption as the primary method and acknowledges the role of simple diffusion.

### Final Answer
The correct explanation for the absorption of amino acids is given in the **first statement**.

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