Which description matches heterochromatin appearance in interphase nucleus as seen by light or electron microscopy?

• A. Lightly staining, less coiled, transcriptionally active.
• B. Found mainly near the nucleolus and not at the periphery.
• C. Euchromatin is located in the nucleolus.
• D. Darkly staining, more coiled, less active chromatin concentrated at the nuclear periphery and around the nucleolus.

Answer: (D)