The number of codons for 20 amino acids are:

Options

A. 62
B. 61
C. 63
D. 64

Explanation

To solve the question regarding the number of codons for the 20 amino acids, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Amino Acids and Codons**:
- There are a total of 20 amino acids that are used in protein synthesis.

**Hint**: Remember that amino acids are the building blocks of proteins.

2. **Total Number of Codons**:
- The genetic code consists of codons, which are sequences of three nucleotides.
- There are 64 possible codons (4 nucleotides: A, U, C, G, and each codon is made up of 3 nucleotides, so 4^3 = 64).

**Hint**: Think about how combinations of nucleotides can form different codons.

3. **Codons for Amino Acids**:
- Out of the 64 codons, 61 codons code for the 20 amino acids.
- The remaining 3 codons are known as stop codons, which signal the termination of protein synthesis.

**Hint**: Distinguish between codons that code for amino acids and those that signal the end of protein synthesis.

4. **Conclusion**:
- Therefore, the number of codons specifically coding for the 20 amino acids is 61.

**Hint**: Focus on the distinction between total codons and those that actually code for amino acids.

### Final Answer:
The number of codons for the 20 amino acids is **61**.