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
Test for colour vision 
Select and explain. 
A. Ishihara plates, B. Holmgren's wool test, C. City university test, D. All the above
D: All the above
Answer: D: All the above 
Explanation: Others
Edridge - Green lantern test.
Fans worth D 15 hue discrimination test.
Nagel's anomaloscope.
Hardy - Rand - Rittler plates.