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Constitutive heterochromatin is defined by its characteristic features, with one of the most significant being that it often contains repetitive sequences. This type of heterochromatin is largely made up of DNA sequences that are repeated multiple times within the genome, such as satellite DNA and certain transposable elements. These repetitive sequences contribute to the structural integrity of chromosomes and play a role in the regulation of gene expression and chromosome stability.

While transcriptional activity is typically associated with euchromatin, constitutive heterochromatin is generally transcriptionally inactive. Additionally, the statement about constitutive heterochromatin being found only near telomeres is overly restrictive, as it can also be located around centromeres and other chromosomal regions. Furthermore, constitutive heterochromatin is not easily visible with all staining techniques, as visibility varies depending on the specific method used and is typically identifiable with specialized techniques that highlight its dense packing. Thus, the option referencing the presence of repetitive sequences accurately captures a defining characteristic of constitutive heterochromatin.