Suppose a scientist is doing an experiment to determine the effect of an all-organic diet on the occurrence of cancer in rats. Which of the following would be the best control group for this experiment?
A. Rats fed a standard rat diet (not organic)
B. Rats fed an all-organic diet
C. Pats fed an all-organic diet, but half the amount of normal
D. Rats that are not fed anything

Hmm... I'm not 100% sure but I'd say it was D.

small, big, or no change could occur in the phenotype. it could cause something as simple as a cats ears to curl backwards or something as frighting as death. it could also occur in the protien-coding area and have an effect on that but no effect on the amino acids. what has to occur is a changing in the hox gene or the control gene.