Question

what is critical in almost every ecosystem?
helium
sunlight

Explanation:

Sunlight is crucial in almost every ecosystem. It is the primary source of energy for photosynthesis, which is the process by which plants convert light energy into chemical energy. This chemical energy is then passed through the food chain, supporting all life forms in the ecosystem. Helium, on the other hand, is a noble gas and does not play a significant role in most ecosystems.

Answer:

Sunlight