This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Microbiology
Microlaryngoscopy is usually done with an objective lens with focal length of 
Select and explain. 
A. 100 mm, B. 200 mm, C. 300 mm, D. 400 mm
D: 400 mm
Answer: D: 400 mm 
Explanation: Surgical microscopes have the ability to fine focus with focal lengths that may vary from the standard microlaryngeal surgical focal length of 400 mm.