Polymerase chain reaction is most useful in

Options

A. DNA synthesis
B. DNA amplication
C. Protein synthesis
D. Aminoacid synthesis

Answer

### Step-by-Step Solution:

1. **Understanding PCR**: The Polymerase Chain Reaction (PCR) is a technique used to amplify a specific segment of DNA, producing millions of copies from a small initial sample.

2. **Identifying the Purpose of PCR**: The primary purpose of PCR is to increase the number of copies of a specific DNA sequence, which is referred to as DNA amplification.

3. **Evaluating the Options**: The question provides four options:
- DNA synthesis
- DNA amplification
- Protein synthesis
- Amino acid synthesis

4. **Analyzing Each Option**:
- **DNA Synthesis**: This is a natural process that occurs in cells; PCR does not synthesize DNA but amplifies existing DNA.
- **DNA Amplification**: This is the correct answer as PCR is specifically designed to create multiple copies of DNA.
- **Protein Synthesis**: This process occurs after DNA has been transcribed into RNA and is not directly related to PCR.
- **Amino Acid Synthesis**: This is part of protein synthesis and not related to the function of PCR.

5. **Conclusion**: Based on the analysis, the most useful application of the Polymerase Chain Reaction is in DNA amplification.

### Final Answer:
**DNA amplification**