Plants capture only ____ of the photosynthetically active radiation (PAR) and this small amount of energy sustains the entire living world.

2-10 percent

The correct answer is Option (3) → 2-10 percent 

Except for the deep sea hydro-thermal ecosystem, sun is the only source of energy for all ecosystems on Earth. Of the incident solar radiation less than 50 per cent of it is photosynthetically active radiation (PAR). Plants and photosynthetic bacteria (autotrophs), fix Sun’s radiant energy to make food from simple inorganic materials. Plants capture only 2-10 per cent of the PAR and this small amount of energy sustains the entire living world. So, it is very important to know how the solar energy captured by plants flows through different organisms of an ecosystem. All organisms are dependent for their food on producers, either directly or indirectly. So there is an unidirectional flow of energy from the sun to producers and then to consumers.