What do the arrows represent in the figure

Flow of  energy in ecosystem.

Explanation: The picture here represents the flow of energy from the producers to consumers.

The first picture shows the plants that takes energy from the sun for the production of glucose by the help of the process known as photosynthesis.

The second picture here is caterpillar who is a primary producer feeding on the plant for its energy needs.

The third picture is a bird who is secondary consumer that is eating the caterpillar for its energy needs.

This shows how the energy travels from the sun→producers→ primary consumer→secondary consumers.

the answer is b & c i believe : )

frequency, z, and the collision density, z, in carbon dioxide (co2), r 180 pm at 30 °c and 120 kpa