Are chromosomes composed of euchromatin?

Chromosomes are composed of both euchromatin and heterochromatin. Euchromatin is the less condensed form of chromatin that is typically associated with active gene expression, while heterochromatin is more condensed and generally contains genes that are not actively expressed. Since chromosomes contain both types of chromatin, stating that they are composed solely of euchromatin is not accurate. Therefore, the correct answer reflects the fact that chromosomes include both euchromatin and heterochromatin in their structure. This nuanced understanding of chromatin types is essential in the study of genetics, as it impacts gene regulation and expression across various cell types and conditions.