Let `alpha` and `beta` be two positive real numbers. Suppose `A_1, A_2` are two arithmetic means; `G_1 ,G_2` are tow geometrie means and `H_1 H_2` are two harmonic means between `alpha` and `beta`, then
A. `A_(1)H_(2)`
B. `A_(2)H_(1)`
C. `G_(1)G_(2)`
D. None of these
