The model shows a progression of complexity in the human body. ?

What is the correct term for the missing location on the model?
A cell
B organ
C organ system
D tissue

3. in the fruit fly, recessive mutation brown, b, causes brown color of the eye and absence of red pigment. recessive mutation p of another independent gene causes purple color of the eye and absence of brown pigment. the cross of a brown-eyed female and purple-eyed male produced wild type eyes. what will be the colors and their ratio in f2?