The domain of the real valued function $f(x)=\log _{\sqrt{2}}\left(\sqrt{x^2+x}+\sqrt{x^2-x}\right)$ is

• A

  $[-1,1]$
• Correct answer
  B

  $(-\infty,-1] \cup[1, \infty)$
• C

  $(-\infty, \infty)$
• D

  $(0, \infty)$

Hence, the correct answer is option: 'B'.