Correct Answer: A

Rationale: The correct instruction for a client prescribed Metronidazole is to avoid drinking alcohol while taking this medication. Consuming alcohol with Metronidazole can lead to a disulfiram-like reaction, causing symptoms such as nausea, vomiting, and flushing. It is crucial to advise clients to abstain from alcohol during the course of treatment to prevent adverse reactions and ensure the effectiveness of the medication.

Correct Answer: B

Rationale: The client's serum calcium level is below the expected reference range, indicating hypocalcemia. Calcium carbonate, an oral form of calcium, is used to increase serum calcium levels to the expected range in cases of hypocalcemia. It helps correct the deficiency by supplementing calcium in the body.

Correct Answer: A

Rationale: The correct instruction is to remove the prior dose before applying a new dose. This helps prevent toxicity by ensuring the client does not inadvertently apply an excessive amount of nitroglycerin.

Correct Answer: B

Rationale: Creatine kinase should be monitored in clients taking Atorvastatin as it can indicate muscle damage, a serious adverse effect of statins. Elevated creatine kinase levels may suggest myopathy or rhabdomyolysis, which are potential complications of statin therapy.

Correct Answer: D

Rationale: The correct answer is D: Headache. Headache during desmopressin therapy can indicate water intoxication, which is a potential adverse effect. Desmopressin is a medication used to treat Diabetes Insipidus by reducing excessive urination and thirst. Monitoring for headaches is crucial as it can signal decreased sodium levels due to water retention, leading to water intoxication, which is a serious concern. Hypovolemia, hypercalcemia, and agitation are not typically associated with desmopressin therapy for Diabetes Insipidus.