Genetic engineering involves :

Options

A. use of restriction endonuclease on bacterial DNA and formation of new traits
B. Use of ligase for cutting DNA
C. Developing instruments
D. Use of statistic in genetics

Explanation

### Step-by-Step Solution:

1. **Understanding Genetic Engineering**: Genetic engineering is a biotechnological process that involves manipulating an organism's DNA to achieve desired traits or characteristics.

2. **Identifying Key Components**: The main components involved in genetic engineering include:
- **Restriction Endonucleases**: Enzymes that cut DNA at specific sequences.
- **DNA Ligase**: An enzyme that joins DNA fragments together.

3. **Process of Genetic Engineering**:
- **Cutting DNA**: The first step involves using restriction endonucleases to cut both the vector DNA (usually a plasmid) and the DNA containing the gene of interest. This creates compatible ends for joining.
- **Joining DNA**: After cutting, the gene of interest and the vector DNA are combined using DNA ligase, which seals the nicks in the sugar-phosphate backbone of the DNA, resulting in recombinant DNA.

4. **Formation of New Traits**: Once the recombinant DNA is formed, it can be introduced into a host organism (often bacteria) where it can express the new traits encoded by the gene of interest.

5. **Evaluating Options**:
- **Option A**: Use of restriction endonuclease on bacterial DNA and formation of new traits - This is correct as it encompasses the cutting and joining of DNA to create new traits.
- **Option B**: Use of ligase for cutting DNA - This is incorrect because ligase is used for joining DNA, not cutting.
- **Option C**: Developing instruments - This is not relevant to the definition of genetic engineering.
- **Option D**: Use of statistics in genetics - While statistics can be involved in genetic studies, it is not a direct part of genetic engineering.

6. **Conclusion**: The correct answer is **Option A**: Use of restriction endonuclease on bacterial DNA and formation of new traits.