Experiment testing CO2 necessity in photosynthesis

Steps:

• Determine experiment goal: remove CO2 while providing light, water, and plant to observe photosynthesis impact.
• Scan options for CO2 manipulation: absorption or detection without removal.
• Confirm presence of light for photosynthesis activation.
• Eliminate setups lacking CO2 control or testing other factors.

Why A is correct:

• Sodium hydrogencarbonate solution absorbs CO2, isolating its role in the photosynthesis equation (6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂), showing reduced activity without it.

Why the others are wrong:

• B: Darkness tests light requirement, not CO2.
• C: Indicator detects CO2 changes but does not remove it for necessity test.
• D: Lacks any CO2 absorption or control mechanism.

Final answer: A