Which label best classifies all three of these steps?
A chemical reaction takes place.
Reactants are gathered in chloroplasts.
Energy is used to make food.
Oxygen is produced and stored in the plant.

Reactants are gathered in chloroplasts.

Explanation:

Photosynthesis is a process unique to autotrophic organisms like plants. It is the process whereby plants use energy from sunlight to make their own food (chemical substance). The photosynthetic process occurs in two stages in the Chloroplast viz: Light dependent stage and light-independent stage.

In the light dependent stage, the plant captures energy from sunlight via its Chlorophyll pigment and uses it to break down water molecules (H2O) in a process called PHOTOLYSIS OF WATER. This process brings about the electrons and protons needed to form NADPH and ATP molecules respectively. This process occurs in the thylakoid membrane of the CHLOROPLAST.

In the light independent stage, also known as Calvin cycle, the plant uses the NADPH and ATP molecules produced in the light stage to reduce Carbondioxide (CO2), which enters through the stomata of the plant, and power the formation of glucose molecule (C6H12O6).

Hence, based on the steps listed by Jeremy for the photosynthetic process, the gathering of reactants (CO2, H2O and light energy) in the Chloroplast of the plant best classifies those steps

they are all solids.