Answer:
The correct answer is internal and external signals regulate the progression of the cell cycle at various critical check points.
Step-by-step explanation:
The cyclic event that helps to prepare the cell for division is termed as cell cycle.Cell cycle are regulated by various internal and external factors which regulates the passage of cell through various critical check point.
For example Maturation promoting factor helps in the progression of frog egg oocytes cells from G2 to M phase.
G1 cyclin CDK helps in the passage of cell from G1 to S phase.