This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Ends of chromosomes replicated by 
Select and explain. 
A. Telomerase, B. Centromere, C. Restriction endonuclease, D. Exonuclease
A: Telomerase
Answer: A: Telomerase 
Explanation: Telomerase is responsible for synthesis of and maintenance of telomere length (end of chromosome).