Final answer:
All four examples (telomeric DNA, Barr body, repetitive DNA, and centromeric DNA) represent heterochromatin, which is highly condensed and typically not expressed.
Step-by-step explanation:
Heterochromatin is a densely packed form of DNA, which is not typically transcribed into RNA, indicating that genes in these regions are usually not expressed. Examples of heterochromatin include the telomeric DNA and centromeric DNA due to their important structural roles and lack of gene activity. The Barr body is a deactivated X chromosome found in female mammals and is another example of heterochromatin, which is characterized by its densely packed form. One more type of heterochromatin is repetitive DNA, which involves sequences that are repeated numerous times in the genome and are also tightly packed.
In summary, all the examples provided in the question: telomeric DNA, Barr body, repetitive DNA, and centromeric DNA, are parts of the chromosome that are heterochromatic due to their densely packed nature and their generally inactive status in terms of gene expression.