Two machines, X and Y, produce earbuds. Let X represent the diameter of an earbud produced by machine X, and let Y represent the diameter of an earbud produced by machine Y. X has a mean of 14 mm with a standard deviation of 0.6 mm, and Y has a mean of 15.2 mm with a standard deviation of 0.2 mm. Which answer choice correctly calculates and interprets the mean of the difference, D = X – Y? Mu Subscript D = –1.2; earbud manufacturers can expect the difference in the diameter of earbuds produced from machines X and Y, on average, to be –1.2 mm. Mu Subscript D = 0.4; earbud manufacturers can expect the difference in the diameter of earbuds produced from machines X and Y, on average, to be 0.4 mm. Mu Subscript D = 1.2; earbud manufacturers can expect the difference in the diameter of earbuds produced from machines X and Y, on average, to be 1.2 mm. Mu Subscript D = 29.2; earbud manufacturers can expect the difference in the diameter of earbuds produced from machines X and Y, on average, to be 29.2 mm.