If $\sin \left(\sin ^{-1} \frac{1}{5}+\cos ^{-1} x\right)=1$ then what is $x$ equal to?

• A

  0
• B

  1
• C

  $\frac{4}{5}$
• Correct answer
  D

  $\frac{1}{5}$

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