This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
DNA or RNA fragment which is radioactive or chemically labile to detect a specific fragment? 
Select and explain. 
A. Probe, B. Okazaki fragment, C. Antibody, D. Epitope
A: Probe
Answer: A: Probe 
Explanation: Probes are generally pieces of DNA or RNA labeled with a 32P-containing nucleotide--or fluorescently labeled nucleotides The probe must recognize a complementary sequence to be effective.Ref: Harper 27e, page no: 456