Stalled forks activate checkpoint signaling and pause replication. G1/S checkpoint checks DNA damage, cell size prior to S - phase (i.e DNA replication phase). This checkpoint would be activated by stalled DNA replication fork.

So, the correct answer is G1/S

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The check point that should be predominantly activated when the cell has completed DNA replication is the G2/M checkpoint. This checkpoint ensures that the DNA has been accurately replicated and any errors have been corrected before the cell enters mitosis.

Explanation:

G1/S Checkpoint:
- This checkpoint occurs in the G1 phase of the cell cycle
- It ensures that the cell has enough nutrients and energy to undergo DNA replication
- It checks for DNA damage and if any damage is found, it halts the cell cycle to allow for repairs

G2/M Checkpoint:
- This checkpoint occurs in the G2 phase of the cell cycle
- It ensures that DNA replication is complete and accurate
- It checks for any DNA damage that may have occurred during replication and repairs it
- It ensures that the cell has enough energy and resources to enter mitosis
- It prevents the cell from entering mitosis until all errors are corrected

M Checkpoint:
- This checkpoint occurs during mitosis
- It ensures that chromosomes are properly aligned and attached to the spindle fibers before the cell enters anaphase
- It ensures that each daughter cell will receive the correct number of chromosomes

Conclusion:

In conclusion, the G2/M checkpoint is predominantly activated when the cell has completed DNA replication. This checkpoint ensures that the DNA has been accurately replicated and any errors have been corrected before the cell enters mitosis.