12. Which case of factoring does the expression x²– 121 belong? A. Common Monomial Factor C. Quadratic Trinomial B. Difference of two Squares D. Perfect Square Trinomial 13. Which case of factoring does the expression x²-16x + 64 belong? A. Common Monomial Factor C. Quadratic Trinomial B. Difference of two Squares D. Perfect Square Trinomial