What is the rate of chemical reaction?

Explanation:

The rate of reaction is the speed at which a chemical reaction takes place, defined as proportional to the increase in the concentration of a product per unit time and to the decrease in the concentration of a reactant per unit time. Reaction rates can vary dramatically.

i'm hoping this is like a multiple answer question. if it is then it would be, the location of the plants and also the height of the plants since one she wants to know where in her garden the chamomile grows best. but also to see which plants grew better in the location she also has to measure the plant itself. (if you can only choose one answer than it would be c).