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
Sympatric speciation occurs when populations of a species that share the same habitat become reproductively isolated from each other. This speciation phenomenon most commonly occurs through polyploidy, in which an offspring or group of offspring will be produced with twice the normal number of chromosomes.