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: Social & Preventive Medicine
Test used to study the ordinal data of two independent groups which are not normally distributed? 
Select and explain. 
A. Student t test, B. z test, C. Single line analysis of variance, D. Wilcoxan signed rank test
D: Wilcoxan signed rank test
Answer: D: Wilcoxan signed rank test 
Explanation: Ans. is 'd' i.e. Wilcoxan signed rank test