Assertion (A): The amino acid glycine predominatly exists in the form of `^(o+)NH_(3)CH_(2)COO^(Theta)`.
Reason (R) : The conjugate acid of glycine is `NH_(2)CH_(2)COO^(Theta)`.

Options

A. If both (A) and (R) are correc, and (R) is the correct explanation of (A).
B. If both (A) and (R) are correct but (R) is not the correct explanation of (A).
C. If (A) is correct, but (R) is incorrect.
D. If (A) is incorrect, but (R) is correct.

Explanation

To solve the question, we need to analyze both the assertion (A) and the reason (R) provided regarding the amino acid glycine.

### Step-by-Step Solution:

1. **Understanding Glycine Structure**:
- Glycine is the simplest amino acid with the chemical formula NH2CH2COOH. It contains both an amino group (NH2) and a carboxylic acid group (COOH).

2. **Zwitterionic Form**:
- In aqueous solutions, glycine predominantly exists in a zwitterionic form, which is a dipolar ion. This occurs when the carboxylic acid group donates a proton (H+) to the amino group, resulting in the structure:
\[ NH_3^+CH_2COO^- \]
- This means that glycine exists mainly as a zwitterion (NH3+ and COO-).

3. **Evaluating Assertion (A)**:
- The assertion states that glycine predominantly exists in the form of \( NH_3^+CH_2COO^- \). This is true because, in solution, glycine does exist mainly in this zwitterionic form.

4. **Understanding Conjugate Acid**:
- The reason states that the conjugate acid of glycine is \( NH_2CH_2COO^- \).
- To find the conjugate acid of glycine, we need to consider the zwitterionic form \( NH_3^+CH_2COO^- \). When this zwitterion accepts a proton (H+), it becomes:
\[ NH_3^+CH_2COOH \]
- Therefore, the correct conjugate acid of glycine is \( NH_3^+CH_2COOH \), not \( NH_2CH_2COO^- \).

5. **Evaluating Reason (R)**:
- Since the reason provided is incorrect (it describes the conjugate base instead of the conjugate acid), we conclude that while the assertion is correct, the reason is not.

6. **Final Conclusion**:
- Therefore, the answer to the question is that the assertion (A) is correct, but the reason (R) is incorrect. This leads us to option 3: "Assertion is correct but Reason is incorrect."