Final answer:
The correct statement indicating understanding of lithium use is that the patient will increase fluid intake. Proper hydration is essential while taking lithium, and a consistent salt intake should be maintained.
Step-by-step explanation:
The correct statement by the patient that indicates an understanding of their responsibility when using lithium for bipolar disorder is: B) I will increase my fluid intake. Lithium is a medication that requires careful management of fluid and electrolyte balance. Patients are advised to maintain a stable and adequate fluid intake to prevent dehydration, which can increase lithium levels and cause toxicity. Additionally, patients should consume a consistent amount of salt (sodium) in their diet, as fluctuations can affect lithium levels. Therefore, patients do not need to intentionally increase or decrease their salt intake unless otherwise directed by a healthcare provider.