This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
[{'content': 'In a village every fifth house was selected for a study. This is an example of - \nSelect and explain. \nA. Simple random sampling, B. Systematic random sampling, C. Stratified random sampling, D. Convenience sampling', 'role': 'user'}, {'content': "Answer: B \nExplanation: Systematic random sample: this is done by picking every 5th and 10th unit at regular intervals. Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 913", 'role': 'assistant'}]