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
Picking every 5th or 10th unit at regular intervals is: 
Select and explain. 
A. Random sampling, B. Systematic sampling, C. Stratified sampling, D. Quota sampling
B: Systematic sampling
Answer: B: Systematic sampling 
Explanation: A systematic sample is obtained by selecting one unit at random and then selecting additional units at evenly spaced interval till the sample of required size has been achieved.