Question

part of the pathway of energy through ecosystems is as follows light → chemical → mechanical. what is the last pathway for energy? water air heat

Explanation:

In ecosystems, energy flow follows the sequence of light (captured by producers via photosynthesis, converted to chemical energy in organic matter), then chemical energy is used for mechanical work (e.g., movement of organisms), and finally, energy is dissipated as heat due to the second law of thermodynamics (energy transformations are not 100% efficient, and some energy is lost as heat at each trophic level or energy transfer). Water and air are not forms of energy in this energy - pathway context.

Answer:

C. heat