This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Paranasal Sinuses, Subject name: ENT
[{'content': 'Sinus absent at the birth: \nSelect and explain. \nA. Maxillary sinus, B. Ethmoidal sinus, C. Frontal sinus, D. Temporal sinus', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) Frontal sinusRef: Dhingra 5th Ed. / 203* Please refer to above table* The first sinus that starts to develop in human embryo is maxillary sinus. It starts to develop around 10 weeks of intra-uterine life.* The last sinus to develop in human embryo is frontal sinus . This sinus is absent at the time of birth & starts to develop postnatally.* Frontal sinus can be visualized radiologically at 6 yrs of age.', 'role': 'assistant'}]