What is the ultimate source of energy for all living organisms on earth ?

Solar energy

The correct answer is Option (4) –Solar energy

The ultimate source of energy for all living organisms on Earth is: Solar energy

Solar energy, in the form of sunlight, is the primary source of energy for nearly all life on Earth. Through the process of photosynthesis, green plants, algae, and some bacteria convert solar energy into chemical energy in the form of glucose. This glucose serves as the primary energy source for these organisms and is also the basis of the food chain, as it provides energy for other organisms that consume plants directly or indirectly. Therefore, solar energy drives the Earth's ecosystems and sustains life on the planet.