This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
[{'content': 'In-situ DNA nick end labeling can quantitate - \nSelect and explain. \nA. Fraction of cells in apoptotic pathways, B. Fraction of cells in S phase, C. p53 gene produce, D. bcr/abl gene', 'role': 'user'}, {'content': 'Answer: A \nExplanation: In Situ Nick-End Labeling An in situ method for detecting areas of DNA which are nicked during APOPTOSIS. Terminal deoxynucleotidyl transferase is used to add labeled dUTP, in a template-independent manner, to the 3 prime OH ends of either single- or double-stranded DNA. The terminal deoxynucleotidyl transferase nick end labeling, or TUNEL, assay labels apoptosis on a single-cell level, making it more sensitive than agarose gel electrophoresis for analysis of DNA FRAGMENTATION. Ref Robbins 9/e p218', 'role': 'assistant'}]