'Microsatellite DNA' is used in the case of which one of the following?

Answer: A. Microsatellite DNA is used for studying evolutionary relationships among species. Microsatellites (also called Simple Sequence Repeats or SSRs) are tandemly repeated DNA sequences of 1-6 base pairs (e.g., CACACA, GTGTGT) distributed throughout the genome. They have high mutation rates and are highly polymorphic, making them excellent genetic markers. Applications include: - Population genetics: studying evolutionary relationships, gene flow, genetic diversity - Phylogeography: mapping species distribution and history - Wildlife forensics: identifying poached animal species and individuals - Paternity testing in animals and humans - Conservation genetics: assessing endangered species Distractors: (B) Stem cell differentiation uses transcription factors and growth factors, not microsatellite DNA. (C) Clonal propagation uses tissue culture, micropropagation; microsatellites only confirm clonal identity. (D) Drug efficacy uses clinical trial protocols, not microsatellite DNA. Source: NCERT Class 12 Biology Ch 6 (Molecular Basis of Inheritance) / standard population genetics texts.