Concept:Mean deviation is the average of the absolute differences between each data value and the mean of the data set.Explanation:Step 1: Find the mean of the data.xˉ=41+2+3+4=410=2.5Step 2: Calculate the absolute deviations from the mean.∣1−2.5∣=1.5∣2−2.5∣=0.5∣3−2.5∣=0.5∣4−2.5∣=1.5Step 3: Sum the absolute deviations.1.5+0.5+0.5+1.5=4Step 4: Divide the sum by the number of values.Mean deviation=44=1.0Answer:The mean deviation is 1.0, which is option A.