Factor the polynomial using special product formulas.

$\frac{x^2}{49}-9$

• A. $\left(\frac{x}{7}-3\right)^2$
• B. $\left(\frac{x}{7}+3\right)\left(\frac{x}{7}-3\right)$
• C. $\left(7x-3\right)^2$
• D. $\left(7x+3\right)\left(7x-3\right)$