Repetitive DNA occurs in

Options

A. satellite DNA
B. transposons
C. heteromeric region of Y chromosomne
D. all of the above

Answer

### Step-by-Step Solution:

1. **Understanding Repetitive DNA**:
- Repetitive DNA refers to sequences of nucleic acids that are present in multiple copies within the genome. These sequences can be classified into different types based on their structure and function.

2. **Analyzing the Options**:
- **Satellite DNA**: This type of DNA consists of tandem repeats of non-coding nucleotide sequences. It is typically found in the centromeric regions of chromosomes and is a classic example of repetitive DNA.
- **Transposons**: Also known as "jumping genes," transposons are segments of DNA that can move from one location to another within the genome. They often consist of repeated sequences and contribute to genetic diversity and evolution.
- **Heterochromatic Region of Y Chromosome**: The Y chromosome contains regions of heterochromatin, which are densely packed and consist of repetitive DNA sequences. This heterochromatin plays a role in the stability and function of the chromosome.

3. **Conclusion**:
- Since all three options (satellite DNA, transposons, and heterochromatic regions of the Y chromosome) contain repetitive DNA, the correct answer to the question "Repetitive DNA occurs in" is **D) All of the above**.