Plant cells cannot conduct light reactions if they do not contain chlorophyll. Chlorophyll is a pigment found in the chloroplasts of plant cells that absorbs light energy for photosynthesis. This pigment is essential for capturing light energy and converting it into chemical energy in the form of ATP and NADPH during the light reactions of photosynthesis.
Without chlorophyll, plants would not be able to absorb light energy from the sun, which is crucial for the initial steps of photosynthesis. Oxygen, carbon dioxide, and glucose are important components or products of photosynthesis, but chlorophyll is specifically responsible for absorbing light energy, making it indispensable for the light reactions to occur in plant cells.
Therefore, the correct answer to the question is:
B. chlorophyll
