Answer:
The answer is D. for at least 14 days
Step-by-step explanation:
In most investigations of a fraud suspect investigations should begin by checking personal and company records, interviewing co-workers, performing invigilations.
If there are symptoms or red flags that a fraud may be occuring , Experts recommended that invigilations must continue for at least 14 days so as to be sure there are no signs or occurrence of fraud