sec^–1(sin²x) is well-defined if and only if

• A

  $\mathrm{x}\in \left[-\frac{1}{2},\frac{1}{2}\right]$

• B

  x ∈ R

• C

  $\mathrm{x}\in \left\{(2\mathrm{n}+1)\frac{\mathrm{\pi }}{2}:\mathrm{n}\in \mathrm{Z}\right\}$

• D

  none of these