Which one of the following statements is true?

Correct option is A

Only option A is correct as it is a property of the median that the sum of absolute deviations measured from the Median is the least.
Options B, C and D are not correct because
 If each value in a given series is multiplied by a constant K, the outcome of the variance is scaled by the square root of that constant.
 variance is the square of the value of the standard deviation.
 Z- score is simply defined as the number of standard deviations from the mean.