Question

All the living organisms ultimately depend on .......... as the ultimate source of energy

Answer 1

The Sun is the major source of energy for organisms and the ecosystems. Producers such as plants, algae, and cyanobacteria use the energy from sunlight to make organic matter from carbon dioxide and water. This establishes the beginning of energy flow through almost all food webs. The continual input of energy, mostly from sunlight, sustains the process of life. Sunlight allows plants to use photosynthesis to convert carbon dioxide and water into organic compounds like carbohydrates which is the fundamental source of organic material in the biosphere.

So the correct option is 'sun/sunlight'.