sentence2_structure: Sunlight<>is<>the main source of energy for all of the organisms in most food chains
sentence1: Plants depend on sunlight for energy, which is ultimately converted into essential nutrients for all the consumers in food chains and webs.
sentence2: Sunlight is the main source of energy for all of the organisms in most food chains.
question: What is the main source of energy for all of the organisms in most food chains?