A desirable change in genotype of an organism is obtained by

Options

A. DNA replication
B. Protein synthesis
C. rDNA technology
D. mRNA formation

Answer

To answer the question "A desirable change in genotype of an organism is obtained by?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Genotype**: The genotype of an organism refers to its genetic makeup, which is determined by the sequence of nucleotides in its DNA.

2. **Identifying the Process**: To achieve a desirable change in the genotype, we need a method that allows us to alter the DNA sequence. The options provided include:
- DNA replication
- Protein synthesis
- rDNA technology
- mRNA formation

3. **Evaluating Each Option**:
- **DNA Replication**: This process simply copies the existing DNA. It does not introduce any changes to the genotype.
- **Protein Synthesis**: This process involves translating mRNA into proteins. While proteins are crucial for an organism's traits, changing proteins does not directly alter the genotype.
- **mRNA Formation**: This is the process of transcribing DNA into mRNA. Like protein synthesis, it does not change the DNA itself.
- **rDNA Technology**: This stands for recombinant DNA technology, which involves altering the DNA of an organism. This method allows scientists to insert, delete, or modify genes, leading to a change in the genotype.

4. **Conclusion**: The only option that directly allows for a desirable change in the genotype of an organism is rDNA technology.

### Final Answer:
A desirable change in genotype of an organism is obtained by **rDNA technology**.

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