Which instruction should the practical nurse (PN) provide to the client prior to discharge?

The correct answer is D: Never scratch under the cast. Scratching under the cast can lead to skin breakdown, infection, or injury. The cast provides protection to the healing area, and scratching can compromise this protection. It is crucial for the PN to emphasize this point to the client to prevent complications. Applying a cold pack (A) may help with swelling but is not the priority here. Keeping the left leg in a dependent position (B) is not necessary for all clients. Expecting an increase in pain (C) may not apply to all cases and can cause unnecessary worry.