With reference to the planet Earth, consider the following statements: I. Rain forests produce more oxygen than that produced by oceans. II. Marine phytoplankton and photosynthetic bacteria produce about 50% of world's oxygen. III. Well-oxygenated surface water contains several folds higher oxygen than that in atmospheric air. Which of the statements given above is/are correct?
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A hard Environment multiple-choice question from UPSC Prelims 2025. Attempt it above, then check the correct answer and detailed explanation below.
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Correct answer: B. II only
Only statement II is correct — marine phytoplankton and photosynthetic bacteria produce roughly half of the world's oxygen. Oceans produce more oxygen than rain forests (I wrong), and surface water holds far less dissolved oxygen than the atmosphere (III wrong).
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