You are answering a USMLE-style medical question. Question: A 34-year-old man with acute lymphocytic leukemia presents for follow-up in the oncology clinic after his second cycle of chemotherapy. In addition to intermittent nausea, he has mild weakness, tingling, and numbness in his left hand. With his affected hand, he is able to grip, but occasionally drops small objects. His oncologist tells him that one of his chemotherapy agents likely caused his neuropathy given its strong association with neurotoxicity. He was recently treated with cyclophosphamide, vincristine, doxorubicin, dexamethasone, and dasatinib. The culprit medication works by which of the following mechanisms of action? Options: A) Covalently X-links DNA B) Blocks microtubule formation C) Intercalates between DNA D) Modifies DNA transcription and protein synthesis Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.