Radiation pertaining to wavelengths suitable for photosynthesis is about:

Correct option is A

Explanation:
Photosynthetically Active Radiation (PAR) refers to the portion of solar radiation (with wavelengths between 400 to 700 nm) that is usable by plants for photosynthesis. Only about 44% of the total incoming shortwave radiation falls within this wavelength range. The rest is either outside this spectral window (like ultraviolet and infrared) or not useful for photosynthesis.
Information Booster:
The total solar radiation reaching the Earth's surface includes:
· Ultraviolet (UV): ~7%
· Visible (PAR): ~44%
· Infrared (IR): ~49%
Of this, PAR (Photosynthetically Active Radiation) is most crucial for plant growth, as chlorophyll pigments absorb light in the blue and red portions of the spectrum. Despite being less than half of the solar input, PAR is the key driver of primary productivity.
Additional Knowledge:
· Option (2), (3), and (4) overestimate the proportion of radiation useful for photosynthesis.
· Only 44% of incident shortwave radiation corresponds to the PAR range (400–700 nm), making option (1) correct.