Sunlight is important in an ecosystem because it:

Evaluate each option by comparing it to the known biological processes: nutrient recycling is mainly done by decomposers, not directly by sunlight; consumers do not receive energy directly from sunlight but from producers; decomposers release energy as heat but do not create energy from sunlight.

Conclude that the correct understanding is that sunlight provides the initial energy input for photosynthesis, which is then transformed into chemical energy that sustains most food webs.