For a primary producer, the main function of photosynthesis is to manufacture:

• A. proteins from sunlight and minerals
• B. glucose from carbon dioxide and water
• C. oxygen from nitrogen and water
• D. ATP from carbon dioxide and oxygen

Answer: (B)

Verified step by step guidance

1. Understand the process of photosynthesis: Photosynthesis is the process by which primary producers (like plants, algae, and some bacteria) convert light energy into chemical energy stored in glucose. This process primarily uses carbon dioxide (CO₂) and water (H₂O) as reactants.
2. Recall the general equation for photosynthesis: The chemical equation for photosynthesis is: $6{\mathrm{CO}}_2+6H_{2}O+\mathrm{light}\to C{6}_{H}O6+6O_2$. This shows that glucose (C₆H₁₂O₆) and oxygen (O₂) are the products of photosynthesis.
3. Analyze the options provided: The question asks about the main function of photosynthesis. Proteins are not synthesized directly from sunlight and minerals, so this option is incorrect. Oxygen is a byproduct, not the main product, and ATP is not directly produced from carbon dioxide and oxygen in photosynthesis.
4. Focus on the correct answer: The main function of photosynthesis is to produce glucose, which serves as an energy source for the organism. This glucose is synthesized from carbon dioxide and water using sunlight as the energy source.
5. Conclude with the correct understanding: The correct answer is 'glucose from carbon dioxide and water,' as this aligns with the primary purpose of photosynthesis in primary producers.