Question: In sample surveys, what is meant by NAME_1?
A: A systematic error in a sampling method that leads to an unrepresentative sample.
B: Prejudice, as in ethnic and gender-related studies.
C: Natural variability seen between samples.
D: Tendency for some distributions to be skewed.
Please eliminate two incorrect options first, then think it step by step and choose the most proper one option. Wrap the entire output in JSON format.
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