The correct option is C Bacteria congregate in these areas because these areas had the most oxygen released
Engelmann performed his experiment by placing oxygen loving bacteria on the alga and illuminating it with light that had been passed through a prism.
He observed that bacteria were concentrated in the area where red and blue light fell.
Their clumping allowed him to see which regions had the highest concentration of oxygen.
He concluded that the most photosynthetically active regions will have the highest concentrations of bacteria.
Therefore, the bacteria accumulated in the regions of red and violet light, showing that these wavelengths of light generated the most photosynthetic activity.