Select the option that can substitute the highlighted segment with the correct idiom.
After finishing this assignment, the employees make it a day.

Correct option is A

The correct idiom to substitute the highlighted segment is (a) "call it a day."
"Call it a day" is a common English idiom used to express that one has decided to stop working on something, usually after a significant amount of effort or at the natural conclusion of the workday.
This fits the context where employees decide to stop working after completing their assignment.
Example: After eight hours of intense study, she decided to call it a day and relax.
Other related idioms:
 Hit the hay: To go to bed.
 Wrap it up: To finish or bring something to an end.
 Pack it in: To stop working or to give up on something.
 Clock out: To officially record the end of one's workday.
 Put a pin in it: To pause a discussion or activity with the intention of resuming it later.