This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autonomic nervous system, Subject name: Pharmacology
Which of the following is the shoest acting mydriatic? 
Select and explain. 
A. Atropine, B. Tropicamide, C. Cyclopentolate, D. Homatropine
B: Tropicamide
Answer: B: Tropicamide 
Explanation: Ref:KD Tripathi pharmacology 6th edition (page.no: 111) Tropicamide has the quickest (20-40 min) and briefest (3--6 hours) action but is a relatively unreliable cycloplegic. However, it is satisfactory for refraction testing in adults and as sho acting mydriatic for fundoscopy. for infants and children, atropine must be used for fundoscopy