Which statement is scientifically based?
a).mutations rarely occur.
b).all mutations are harmful.
c).some mutations can be contagious, like infections.
d).mutations are not passed from parent to offspring.

Which of the following are not matched correctly? cd8+: directly destroy infected or cancerous cells t reg cell: reduce the adaptive response once threat passes t l: activate cellular branch (cytotoxic t cells, macrophages, nk cells) t 2: stimulate b cells to make antibodies t (cd4+): mhc i