Which of the following does not produce oxygen as a product of photosynthesis?

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Which of the following does not produce oxygen as a product of photosynthesis? Answer: Purple sulfur bacteria

Question context

This question is part of 🦠 Microbiology within the broader 🧬 Medical Science subject and appears in the DemoPaper-Pakistan preparation collection. Reviewing the answer together with nearby questions helps reinforce the underlying concept and identify how it may appear in competitive exams.