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: Medicine
In ethambutol toxicity there will be loss of ability to see which of the following colour? 
Select and explain. 
A. Red, B. Green, C. Blue, D. Yellow
B: Green
Answer: B: Green 
Explanation: Optic neuritis, the most serious adverse effect repoed, typically presents as reduced visual acuity, central scotoma, and loss of the ability to see green (or, less commonly, red). Ref: Harrisons Principles of Internal Medicine, 18th Edition, Page 1376.