Final answer:
The best time for a nurse to assess a client for residual urine is immediately after the client voids, as this allows for determining if any urine is left in the bladder, which might indicate urinary retention problems.
Step-by-step explanation:
The best time to assess a client for residual urine is A. Immediately after the client voids. Residual urine refers to the urine that remains in the bladder after a person attempts to empty it completely. Assessing for residual urine is essential in identifying potential issues such as obstruction or neurological disorders that could impair bladder function. This measurement can be performed using bladder ultrasound or catheterization post-void. It is important for preventing urinary tract infections and other complications associated with urinary retention.