Question

Cell in $G_0$ phase.
A) Exit the cell cycle.
B) Enter the cell cycle.
C) Suspend the cell cycle.
D) Terminate the cell cycle.

Answer 1

The cell cycle, or cell-division cycle, is the events that take place in series inside a cell which result in division into two daughter cells. These series events include the replication of DNA and its organelles, and also the partitioning of its cytoplasm and other components into two daughter cells in a process called cell division. In every hour about one billion cells die and one billion cells are made in the body.

Complete answer:
Cell cycle has four distinct phases:- $G_1$ phase, S phase (synthesis), $G_2$ phase (collectively known as interphase) and M phase (mitosis and cytokinesis).
M phase is a combination of two processes:- mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm divides, forming two daughter cells.
Activation of the next phase is totally dependent on the proper development and completion of the last phase. Cells that have semi-permanently or reversibly stopped dividing are part of the cycle called $G_0$ phase.

Hence, the correct answer is Exit of the cell cycle.

Note: The cell cycle initiates with the $G_0$phase. The cells which are not dividing are entering the quiescent $G_0$ state from $G_1$ and may stay in $G_0$ for long periods of time. Some of the cells enter the $G_0$ phase semi-permanently and are understood as post-mitotic.