Let \( f(x) = \frac{1}{7 - \sin 5x} \) be a function defined on \( \mathbb{R} \). Then the range of the function \( f(x) \) is equal to:
\( \left[ \frac{1}{7}, \frac{1}{6} \right] \)
\( \left[ \frac{1}{8}, \frac{1}{6} \right] \)
\( \left[ \frac{1}{8}, \frac{1}{5} \right] \)
\( \left[ \frac{1}{7}, \frac{1}{5} \right] \)