Step 1: Analyze the symmetry of the function.
The given function \( \log \left( \frac{7 - x}{7 + x} \right) \) is an odd function because replacing \( x \) with \( -x \) results in the negative of the original function. The integral of an odd function over a symmetric interval \( [-a, a] \) is 0.
Step 2: Conclusion.
Thus, the value of the integral is 0, corresponding to option (B).