Explanation:

The correct answer is A (trimmed mean). A trimmed mean is calculated by excluding a specified percentage of the lowest and highest values from a dataset and then computing the arithmetic mean of the remaining values. For instance, a 5% trimmed mean discards the lowest 2.5% and the highest 2.5% of values and calculates the mean of the remaining 95%.

• B (harmonic mean) is incorrect because it involves summing the reciprocals of the observations, averaging them, and then taking the reciprocal of the result. It does not exclude outliers.

• C (winsorized mean) is incorrect because it replaces the extreme values (lowest and highest) with specified percentiles rather than excluding them entirely, and then computes the mean of the adjusted dataset.