Question

which of these could be a depletable energy resource, if not managed correctly?
solar
wind
forests

Explanation:

Solar and wind are renewable energy sources with essentially unlimited supply (solar from the sun, wind from atmospheric processes). Forests, if not managed (e.g., over - harvesting without replanting), can be depleted as a biomass energy resource (or for other uses), as trees take time to grow and replace.

Answer:

forests