The domain of the function \( \cos^{-1}\!\left( \dfrac{2 \sin^{-1}\!\left( \dfrac{1}{4x^{2}-1} \right)}{\pi} \right) \) is:
\( \mathbb{R} - \left\{ -\dfrac{1}{2}, \dfrac{1}{2} \right\} \)
\( (-\infty, -1] \cup \left[ \dfrac{1}{2}, \infty \right) \cup \{0\} \)
\( \left( -\infty, \dfrac{-1}{2} \right) \cup \left( \dfrac{1}{2}, \infty \right) \cup \{0\} \)
\( \left( -\infty, \dfrac{-1}{\sqrt{2}} \right] \cup \left[ \dfrac{1}{\sqrt{2}}, \infty \right) \cup \{0\} \)