Englemann's experiment with Spirogyra demonstrated that

Options

A. The full spectrum of sunlight is needed for photosynthesis
B. Only red wavelengths are effective in causing photosynthesis
C. Only blue wavelengths are effective
D. Both blue and red wavelengths are effective

Answer

D

Explanation

In 1881 Engelmann. uses the light of visible spectrum of different wavelength. The bacteria accumulated in the region of red and blue light showing that this wavelength of light generates the most photosynthetic activity.