You are answering a USMLE-style medical question. Question: A 30-year-old woman presents to your office with decreased appetite, malaise, and fever. Serologic tests reveal positive Anti-HBsAg and Anti-HAV IgM antibodies. Which of the following is most likely responsible for this patient's presentation? Options: A) Needlestick B) Unprotected sex C) Shellfish D) Acetaminophen overdose Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.