According to NCERT page number 245 chapter ecosystems incident solar radiation less than 50% of its photosynthetically active radiation Then option D will correct.
Less than 50% Aisa ek hi option h jisme kam hai

The correct answer is option 'D' (2-10%).

Photosynthetically Active Radiation (PAR) refers to the portion of the electromagnetic spectrum that is utilized by plants for photosynthesis. It ranges from 400 to 700 nanometers and corresponds to the visible light spectrum.

Here is an explanation of why the percentage of PAR captured by plants in the synthesis of organic matter is relatively low:

1. Absorption Spectrum:
- Plants have pigments called chlorophylls that are responsible for capturing light energy.
- The absorption spectrum of chlorophylls shows that they have peak absorption in the blue (around 430-450 nm) and red (around 640-680 nm) regions of the spectrum.
- The absorption of light in these specific wavelengths is essential for driving photosynthesis.

2. Reflectance and Transmittance:
- Not all the PAR that reaches a plant's surface is absorbed.
- Some of the light is reflected back into the environment.
- Other wavelengths are transmitted through the plant's tissues and are not utilized for photosynthesis.

3. Light Saturation Point:
- The rate of photosynthesis initially increases with increasing light intensity.
- However, there is a point beyond which the photosynthetic rate plateaus, known as the light saturation point.
- Beyond this point, additional light does not increase the rate of photosynthesis, as the plant becomes saturated with light energy.

4. Light Compensation Point:
- The light compensation point is the light intensity at which the rate of photosynthesis equals the rate of respiration.
- Below this light intensity, the rate of photosynthesis is lower than respiration.
- This means that plants require some minimum level of light to sustain their metabolic processes.

5. Absorption Efficiency:
- Even when light is within the absorption spectrum of chlorophylls, not all of it is efficiently captured.
- Some photon energy may be dissipated as heat or lost as fluorescence.
- The efficiency of light capture varies between different plant species and environmental conditions.

Based on these factors, the percentage of PAR that is actually captured by plants in the synthesis of organic matter is relatively low, ranging from 2% to 10%. The rest of the PAR is either reflected, transmitted, or not efficiently utilized for photosynthesis.