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: Dental
Statistical test used to relate two group values/ differences? 
Select and explain. 
A. Kruskal Wallis, B. Spearman correlation, C. Kendall tau, D. Chi square
D: Chi square
Answer: D: Chi square 
Explanation: None