Final answer:
The nurse should inform the client that muscle pain is expected with the medication, but weakness is not a common side effect.
Step-by-step explanation:
The correct drug-specific teaching the nurse should provide to this client is mentioned in option C: 'Muscle pain is expected, but weakness is not related to the medication.' Atorvastatin (Lipitor) belongs to a class of medications called statins, which can cause muscle pain as a common side effect. However, muscle weakness is not typically associated with this medication.