This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy, Development and clinical examination, Subject name: Ophthalmology
[{'content': 'Volume of the orbit is \nSelect and explain. \nA. 120ml, B. 100ml, C. 60ml, D. 30ml', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Volume of the orbit is 30ml Orbit" can refer to the bony socket, or it can also be used to imply the contents. In the adult human, the volume of the orbit is 30 millilitres (1.06 imp fl oz; 1.01 US fl oz), of which the eye occupies 6.5 ml (0.23 imp fl oz; 0.22 US fl oz). Ratio of volume of orbit to eyeball is 4.5:1 Reference: Aravind FAQS in Ophthalmology; First Edition; Page no: 577', 'role': 'assistant'}]