Aflu vaccine is needed seasonally to be effective but a polio vaccine is only needed once. the best explanation of this is

b is the best answer for this question.

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.