Which of these describes something that would increase the validity of an experiment?

controlling more variables

improving measurement technique

increasing randomization to reduce sample bias

blinding the experiment

adding control or placebo groups

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.