This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostatistics, Subject name: Social & Preventive Medicine
What is the method of sampling in which the units are picked up at regular intervals from the universe- 
Select and explain. 
A. Simple random sampling, B. Systematic random sampling, C. Stratified random sampling, D. Snow - ball sampling
B: Systematic random sampling
Answer: B: Systematic random sampling 
Explanation: .