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.
Answer:
The independent variable is the amount of sunlight.
The dependent variable is the growth.
The question is incomplete.
The distance between the Moon and Earth influences: 1) the attractive gravitational force between them, 2) the tides, 3) the eclipses, 4) the period of each full turn of the moon around the Earth.
Assuming the question refers to the gravitational attraction, we must use the fact that, as per, Newton's Universal Gravitaional Law, the attractive force between the two bodies is inversely related to the square distance that separates them.
Then, if the Moon were twice as far, the gravitational pull would be one fourth (1/4) of actual pull.
C. Age structure. Hope I helped :)
