Concept:The epididymis is the coiled tube where sperm mature and are temporarily stored after leaving the testes.Explanation:The testes produce sperm, but the sperm are not stored there.The sperm pass into the epididymis, where they are stored temporarily until ejaculation.The sperm duct (vas deferens) mainly transports sperm during ejaculation, not for temporary storage.Answer:A. epididymis.