You are answering a USMLE-style medical question. Question: A 20-year-old woman comes to the clinic for her first follow-up visit after being diagnosed with bipolar I disorder 1-month ago. At that time, she was acutely severely manic and was brought to the emergency department by her concerned boyfriend. She was started on lithium, and after subsequent improvement, she was discharged. A week after discharge, the patient forgot to take her medication for a few days and quickly began to manifest manic symptoms again which required brought her to the emergency department again. Since then, she has been compliant with her medications and currently has no significant complaints. Which of the following recommendations would be most helpful in minimizing the risk to the fetus in this patient? Options: A) Adjust dosage of medication throughout the pregnancy B) Supplement all patients with 5mg of daily folic acid C) Low-dose polytherapy is preferred over monotherapy D) Switch to valproate as it has safest pregnancy profile Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.