The difficulty some units face adapting their mindset to vastly changed conditions on their third or fourth deployment to the same location is known as challenges.

Rotation Challenge.

Explanation:

Job Rotation can be defined as a practice of employers to shift or rotate from one task to another to promote experience. There are pros and cons to job rotation activities. Employees who are shifted from one task to the other finds it difficult to adapt their mindset to a particular task.

This rotation can also lead to less production in a company because an employee is not able to adapt the required skills quickly in such a fast pace shifting world.

So, the correct answer is rotation challenges.

the answer to your question is,

d. when a child was born.

-mabel < 3