What is the range of visible part of the spectrum for photosynthetically active radiations?

Correct option is A

· Photosynthetically Active Radiation (PAR) refers to the range of the electromagnetic spectrum that plants use for photosynthesis.
· This range falls within 400-700 nm, which includes blue, green, and red light.
· Chlorophyll absorbs light most effectively in the blue (400-500 nm) and red (600-700 nm) regions of the spectrum.
· Light outside this range (e.g., infrared or ultraviolet) is not efficiently utilized for photosynthesis.
Thus, the correct option is (a) 400-700 nm.