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: Ophthalmology
[{'content': 'If the axial length of the eyeball is changed by limn then the power changes by: \nSelect and explain. \nA. 1 dioptre, B. 2 D, C. 3 D, D. 4 D', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. 3 Dioptres A decrease in 1 mm in curvature of cornea leads to hypermetropia of 6D while 1 mm decrease in length leads to hypermetropia of 3D.Q', 'role': 'assistant'}]