Step 1: Concept $\sin \theta = 1$ implies $\theta = \pi/2$ (for principal values).
Step 2: Meaning $\sin^{-1} (1/5) + \cos^{-1} x = \sin^{-1} 1 = \pi/2$.
Step 3: Analysis We know the identity $\sin^{-1} A + \cos^{-1} A = \pi/2$ for all $|A| \le 1$.
Step 4: Conclusion By comparing $\sin^{-1} (1/5) + \cos^{-1} x = \pi/2$ with the identity, we get $x = 1/5$.
Final Answer: (A)