If x is an integer and 9<x^2<99, then what is the value of maximum possible value of x minus minimum possible value of x?

A. 5

B. 6

C. 7

D. 18

E. 20

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Also tricky. Notice that can take positive, as well as negative values to satisfy , hence can be: -9, -8, -7, -6, -4, 4, 5, 6, 7, 8, or 9. We asked to find the value of , ans since and then .

Answer: D.