Suppose you want to test the hypothesis that plants grow taller when they receive more sunlight. identify and independent variable and a dependent variable for this investigation.

The result that should be established is in the form
y = f(x) 
where x, the amount of sunlight is the controlled (independent) variable,
y =  height (growth) that corresponds to the amount of sunlight. Therefore y depends on x.

Clearly,
x, the amount of sunlight is the independent variable. It can be controlled.
y, the measured amount of growth is the dependent variable.

The independent variable is the amount of sunlight.
The dependent variable is the growth.

Sorry i don’t know what to do