Answer:
A
Step-by-step explanation:
I'm pretty sure it's A because:
A- The kind of pots doesn't affect the growth of the plant
B- The size of the leaf changes according to the sunlight
C- The volume of water the plants receive is a variable that if changed can change a lot of the plants to a point where it can kill them.
D- The amount of light a plant receives is crucial to the plant, it is not an independent variable