Rachel wants to test how sunlight impacts plant growth over time.
She will add varying amounts of
light to different sets of plants.
The sunlight is a(n)

Independent variable

Explanation:

In a scientific experiment, the variable that an experimenter varies or controls is called an independent variable. This variable has a direct impact on dependent variable.

In the question, Rachel wants to test how sunlight  impacts plant growth over time. Now as sunlight impacts plant growth this means sunlight is an independent variable whereas the plants are dependent variable as the amounts of sunlight impact the plants. Also Rachel changes/varies or controls the amounts of sunlight to different sets of plants. Hence from the above definition of an independent variable it is clear that sunlight is an independent variable.

answer; (trauma);

answer; love and belonging needs;