What Might Prevent a Cell from Passing the G₁ Checkpoint

Multiple Choice

What might prevent a cell from passing the G₁ checkpoint?

A) The DNA has not completed replication.
B) The cell may need to enter the G₀ stage.
C) The cell may have damaged DNA and need to undergo apoptosis.
D) Only A and B are correct.
E) Only B and C are correct.