What can cause cancer to develop? A. Synthesis of a repressor protein

B. Disruption of the cell cycle

C. Turning off of genes during differentiation

D. Structural genes that are active

what's the rest of the question

the statement is true

sex cells are usually half's then they find another half and make a fertilize egg

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.