Telomerase is an enzyme which is a :

Telomerase is an enzyme that is responsible for lengthening telomeres, the protective caps at the ends of chromosomes. It is a ribonucleoprotein, meaning it is composed of both RNA and protein components. The RNA component of telomerase serves as a template for the addition of nucleotides to the telomere, while the protein component has the catalytic activity necessary for this process. Therefore, the correct answer is option (D) ribonucleoprotein. Think of it this way: telomerase is a complex enzyme that uses its RNA component as a template to add nucleotides to the ends of chromosomes, thus maintaining telomere length.