ii. Dependent variable(s): Size of goldfish population iii. Control variables: The type and amoumt of food, the maintenance of the tanks, and the water temperature. b. To determine if the type of agar...

I am having trouble figuring out the variables for this problem. I know that the agar is an independent variable but I am not sure if the E. Coli is also an independent variable . Thank you .

Extracted text: ii. Dependent variable(s): Size of goldfish population iii. Control variables: The type and amoumt of food, the maintenance of the tanks, and the water temperature. b. To determine if the type of agar affects bacterial growth, a scientist cultures E. coli on four different types of agar. Five petri dishes are set up to collect results: one with nutrient agar and E. coli, one with mannitol-salt agar and E. coli, one with MacConkey agar and E. coli, one with LB agar and E. coli, one with nutrient agar but NO E. coli. All of the petri dishes received the same volume of agar, and were the same shape and size. During the experiment, the temperature at which the petri dishes were stored, and at the air quality remained the same. After one week the amount of bacterial growth was measured. Independent variable(s):nsert response here