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
Shadow test is used in ? 
Select and explain. 
A. Keratometry, B. Ophthalmoscopy, C. Gonioscopy, D. Retinoscopy
D: Retinoscopy
Answer: D: Retinoscopy 
Explanation: Ans. is 'd' i.e., Retinoscopy Retinoscopy, also called skiascopy or shadow test, is an objective method of finding out the error of refraction by the method of neutralization.