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
Square root of pq/n indicates: 
Select and explain. 
A. Standard error of mean, B. Standard error of difference of means, C. Standard error of proportions, D. Standard error of difference in proportions
C: Standard error of proportions
Answer: C: Standard error of proportions 
Explanation: None