What is $\log \left(a+\sqrt{a^2+1}\right)+\log \left(\frac{1}{a+\sqrt{a^2+1}}\right)$ equal to?

• A

  1
• Correct answer
  B

  0
• C

  2
• D

  $\frac{1}{2}$

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