Which organism most likely has 10% of the Sun's energy available for its use?

Mouse

Elm tree

Snake

Hawk

The primary consumer in a food chain that would receive 10% (converted to biomass) of the Sun's energy is the mouse. The Elm tree would receive all (100%), the mouse follows as it eats greens, then the snake as it eats mice, then the hawk as top in the food chain in terms of the energy from the Sun itself.