It is the rib cage (thoracic cage)
Explanation:
Cancer occurs in dividing cells only because genetic materials divide into two equal portions during division. This process may be interrupted by carcinogenes or mutagenes to make mutate cells and then render them as cancer cells. In the brain, the cells are differentiated and there is no chance to start division, then how can cancer be found in the brain.
WW and ww would make D. All wrinkled seeds, no smooth seeds.
Your answer is B, cell wall.
