Types of amino acids universally used in protein synthesis are -
a) 20
b) 80
c) 64
d) 61

Options

A. 20
B. 80
C. 64
D. 61

Answer

To answer the question regarding the types of amino acids universally used in protein synthesis, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Amino Acids**: Amino acids are the building blocks of proteins. They are organic compounds that combine to form proteins, which are essential for various biological functions.

2. **Identifying the Total Number of Amino Acids**: In total, there are 20 different amino acids that are universally used in the synthesis of proteins in living organisms.

3. **Classification of Amino Acids**: Among these 20 amino acids:
- **Essential Amino Acids**: There are 9 essential amino acids that must be obtained through diet because the body cannot synthesize them.
- **Non-Essential Amino Acids**: There are 11 non-essential amino acids that the body can synthesize on its own.

4. **Conclusion**: Since the question specifically asks for the types of amino acids that are universally used in protein synthesis, the answer is 20.

5. **Final Answer**: Therefore, the correct option is (a) 20.