This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Parasitology, Subject name: Microbiology
[{'content': 'Trichomoniasis is transmitted through which stage: \nSelect and explain. \nA. Cyst, B. Oocyst, C. Sporozoite, D. Trophozoite', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. D. Trophozoitea. Trichomonas vaginalis exists only as a trophozoite; no cyst stage has been identifiedb. A cyst, oocyst and sporozoite are stages involved in transmitting other protozoan infections, and an egg is the means of transmission in a number of helminth infections.', 'role': 'assistant'}]