Which of the following most used in genetic engineering?

Options

A. E. coil and Agrobacterium
B. Mycobacteria and Salmonella
C. Aspergillus
D. Penicillum

Explanation

**Step-by-Step Solution:**

1. **Understand the Question**: The question asks which organism is most commonly used in genetic engineering.

2. **Analyze the Options**: The options provided are:
- a. E. coli and Agrobacterium
- b. Mycobacteria and Salmonella
- c. Aspergillus
- d. Penicillin

3. **Identify Commonly Used Organisms in Genetic Engineering**:
- **E. coli**: This bacterium is widely used in molecular cloning and genetic engineering because it is easy to manipulate and can express foreign genes.
- **Agrobacterium**: This bacterium is known for its ability to transfer DNA to plants, making it an important tool in plant genetic engineering.

4. **Evaluate Other Options**:
- **Mycobacteria and Salmonella**: These are not commonly used in genetic engineering.
- **Aspergillus**: This is a genus of fungi, but it is not as commonly used as E. coli or Agrobacterium in genetic engineering.
- **Penicillin**: This is an antibiotic and not an organism used in genetic engineering.

5. **Conclusion**: The most commonly used organisms in genetic engineering are E. coli and Agrobacterium, making option (a) the correct answer.

**Final Answer**: a. E. coli and Agrobacterium

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