Step 1: Use the addition formula for arctangent.
We can use the identity for the sum of two arctangents:
\[
\tan^{-1} a + \tan^{-1} b = \tan^{-1} \left( \frac{a + b}{1 - ab} \right)
\]
We apply this identity sequentially to sum all four terms in the given expression. After performing the calculations, we find that the sum of these arctangents is \( \frac{\pi}{4} \).
Step 2: Conclusion.
Thus, the correct answer is \( \frac{\pi}{4} \), corresponding to option (C).