Which rationalization strategy should you use for $\frac{1}{\sqrt{5}+\sqrt{7}}$ and why?

• A. Multiply the numerator and denominator by $\sqrt{7}$, since multiplying by a single radical will rationalize a two-term denominator.
• B. No rationalization is needed because $\sqrt{5}+\sqrt{7}$ is already in simplest form.
• C. Multiply the numerator and denominator by the conjugate $(\sqrt{5}-\sqrt{7})$, since a two-term denominator can be rationalized using the difference of squares.
• D. Multiply the numerator and denominator by $\sqrt{5}$, because multiplying by $\sqrt{5}$ will eliminate the radical in the denominator.

Answer: (C)