This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
[{'content': 'All of the following are features of an injury to the cervical sympathetic trunk EXCEPT: \nSelect and explain. \nA. An hydrosis, B. Enophthalmos, C. Mydriasis, D. Ptosis', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]