You are answering a USMLE-style medical question. Question: A student studying pharmacology is a member of a team that is conducting research related to the elimination of multiple anticoagulant medications. His duty as a member of the team is to collect serum samples of the subjects every 4 hours and send them for analysis of serum drug levels. He is also supposed to collect, document and analyze the data. For one of the subjects, he notices that the subject is eliminating 0.5 mg of the drug every 4 hours. Which of the following anticoagulants did this patient most likely consume? Options: A) Warfarin B) Enoxaparin C) Fondaparinux D) Apixaban Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.