Answer:
growth of plants
Step-by-step explanation:
The variable which changes on its own is called the independent variable and the variable which changes according to the changes in the independent variable is called the dependent variable.
Here the growth of the plants is observed under light of different colors. So, Suzie is has placed 5 ferns and placed them under different color lights. She also keeps the other factors such as amount of water the plants receive the same. She measures the different color lights have on growth of the plants.
Hence, here the dependent variable is the growth of the plants and the independent variable is the color of the lights.