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
The focal length of the lens is 0*75 m, what will be its refractive power - 
Select and explain. 
A. 0.75D, B. 1.5D, C. 1.33 D, D. 1.25 D
C: 1.33 D
Answer: C: 1.33 D 
Explanation: The focal length (f) of a lens is the distance between the optical centre and the principal focus.
Power of a lens (P) is defined as the ability of the lens to converge a beam of light falling on the lens.
It is measured as reciprocal of the focal length in metres i.e. P = 1/f, The unit of power is dioptre (D). One dioptre is the power of a lens of focal length one metre.