The process of cellular respiration is represented by arrow B, only.
Cellular respiration is the process by which cells convert glucose into ATP, the molecule that powers muscle activity.
So, the arrow that represents cellular respiration is the one that goes from glucose to ATP.
The other arrows in the diagram represent other processes that are involved in the flow of energy through an ecosystem.
Arrow A represents the transfer of energy from the sun to plants through photosynthesis.
Arrow C represents the transfer of energy from ATP to muscle activity.
Therefore, the answer is B. arrow B, only.