Polynomials - Difference of squares

SOURCE:COMPETITION
Number of Problems: 1. : (Book)

1.

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The fraction $frac{left(3^{2008} ight)^2-left(3^{2006} ight)^2}{left(3^{2007} ight)^2-left(3^{2005} ight)^2}$ simplifies to which of the following?

$mathrm{(A)} 1qquadmathrm{(B)} frac{9}{4}qquadmathrm{(C)} 3qquadmathrm{(D)} frac{9}{2}qquadmathrm{(E)} 9$

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