C because we are testing the effectiveness of Fertilizer X and Y and using no fertilizer can help determine if that would be better than using a fertilizer. Additionally, a control group of no fertilizer would be the third plant as that is considered normal for the experiment. Msg me for any more questions
The organism that is most specialized would be the sponge
<span>Lynn Margulis supported the endosymbiotic theory and
studied mitosis in cells. She was an American evolutionary theorist who made
great significance in the symbiosis of organisms in biological evolution. She
is also a developer of the Gaia Theory, which believes that the Earth functions
as a single self-regulating system. </span>
Because of the tortoises that were on the islands they had adapted to their surroundings for food so their necks got longer.