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The harmonic mean of two numbers x and y, symbolized as h(x, y), is defined as 2 divided by the sum of the reciprocals of x and y, whereas the geometric mean g(x, y) is defined as the square root of the product of x and y (when this square root exists), and the arithmetic mean m(x, y) is defined as (x + y)/2. For which of the following pairs of values for x and y is g(x, y) equal to the arithmetic mean of h(x, y) and m(x, y)?
(A) x = -2, y = -1
(B) x = -1, y = 2
(C) x = 2, y = 8
(D) x = 8, y = 8
(E) x = 8, y = 64