A 71-year-old woman is brought in by her daughter due to dizziness. The daughter is worried about the potential for a fall, especially since her mother recently (10 days ago) had surgery for a right ankle fracture. The patient denies syncope, but she feels lightheaded when she tries to stand. She lives alone and is in a walking boot with crutches. She admits that she does not feel very stable walking, but she had not been dizzy and lightheaded until 2 days ago. She has not had to use her narcotic pain medicine for the last 5 days, stating her ankle pain is controlled with ibuprofen alone. She had been limiting fluid intake so that she does not require frequent trips to the bathroom, preferring to remain in a chair all day.
Her past medical history is remarkable for stable overactive bladder and hypothyroidism. Medications include oxybutynin, ibuprofen, and levothyroxine. Her only surgery is the recent ankle fracture repair. She denies allergies and use of tobacco, alcohol, and recreational drugs.
On physical exam, the patient is wearing the boot and reports dizziness as she moves to the exam table. Exam is remarkable for mild tachycardia and decreased skin turgor, with the remainder of exam being normal. She is hypovolemic and hypernatremic.

Appropriate intravenous fluid therapy is initiated. Assuming none of this patient's medications are outside normal dosing parameters, what is the most appropriate pharmaceutical intervention for her fluid and sodium status?
a. Administering isotonic saline solution to correct hypovolemia and hypernatremia.
b. Adjusting the dosage of oxybutynin to reduce the risk of exacerbating hypovolemia and hypernatremia.
c. Monitoring and adjusting the dosage of ibuprofen to ensure proper pain management while minimizing the risk of exacerbating hypovolemia and hypernatremia.
d. Counseling the patient on the importance of maintaining adequate fluid intake and closely monitoring her fluid and sodium status.