UPSC Prelims 2022— Question 99

This question belongs to Science & Technology and tests DNA Barcoding. The question tests the underlying scientific or technological principle rather than merely the name of a technology. The correct option is the one consistent with how the system actually works, while attractive distractors usually confuse related technologies or applications. Option D is the keyed answer because 2 and 3 is the combination or identification that satisfies the conditions in the question. A useful way to solve the question is to separate the individual propositions from the answer-code combinations. A statement can look broadly reasonable while still being incorrect because it uses an absolute term, assigns a function to the wrong institution, confuses two related concepts, or places a feature in the wrong region or period. The keyed response should therefore be treated as the outcome of checking each proposition rather than as a memory-only exercise. Option A: 1 only — this is not the correct choice. It fails the question's test because it does not represent the required combination, institution, location, mechanism or historical association. The distractor is plausible only if a related concept is confused with the one actually asked. Option B: 3 only — this is not the correct choice. It fails the question's test because it does not represent the required combination, institution, location, mechanism or historical association. The distractor is plausible only if a related concept is confused with the one actually asked. Option C: 1and 2 — this is not the correct choice. It fails the question's test because it does not represent the required combination, institution, location, mechanism or historical association. The distractor is plausible only if a related concept is confused with the one actually asked. Option D: 2 and 3 — this is the correct choice under the final key. It matches the relevant DNA Barcoding principle and satisfies the question's wording. The exam-oriented takeaway is to identify the governing fact first and only then map it to the answer code. This reduces errors caused by choosing an option because one individual statement appears familiar. For database use, the classification and explanation should be read together: the subject gives the broad domain, the topic identifies the recurring UPSC theme, and the subtopic records the precise knowledge point tested. This also makes the question useful for later topic-wise search and revision.