A patient with diagnosed bipolar disorder was hospitalized 7 days ago and has been taking lithium 600 mg tid. Staff observes increased agitation, pressured speech, poor personal hygiene, and hyperactivity. Which action demonstrates that the nurse understands the most likely cause of the patient's behavior?

A) Educate the patient about the proper ways to perform personal hygiene and coordinate clothing.
B) Continue to monitor and document the patient's speech patterns and motor activity.
C) Ask the health care provider to prescribe an increased dose and frequency of lithium.
D) Consider the need to check the lithium level. The patient may not be swallowing medications.