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
[{'content': 'The true statement about characteristics of a representative sample are: \nSelect and explain. \nA. Its size should be 30 or more–larger the sample, lesser would be the error due to chance., B. It should randomly be selected by an appropriate sampling technique so that each member of the population has an equal opportunity of being selected., C. Both, D. None', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The essential characteristics of a representative sample are:\n\nIts size should be 30 or more–the larger the sample, lesser would be\xa0the error due to chance.\nIt should randomly be selected by an appropriate sampling\xa0technique so that each member of the population has an equal\xa0opportunity of being selected.\n\nThe rules for selection should be independent of the observation\xa0to be made. If the sample represents the population, its values or\xa0statistics like Mean, SD(s) or proportion (p) will not differ\xa0significantly from population parameters or true value μ, σ or P,\xa0respectively. Difference found will not exceed the chance error. If you pick up an apple of any size from a heap, it does not\xa0represent the entire lot. It may be of big, small or medium size. Its\xa0size and weight may not be equal to the mean size and weight of\xa0the lot. If you pick up 30 at random after mixing all sizes, you will\xa0get a representative sample of 30 apples representing the entire\xa0heap (sufficiently large and unbiased). The seller can then fix the\xa0rate of 30 apples from any side of the heap, not allowing the customer\xa0to choose.', 'role': 'assistant'}]