Step 1: Take a numerical example:
Take the 3-4-5 triangle with $x = 3$, $y = 4$, $z = 5$. Then $x + z = 8$ and $z - x = 2$.
Step 2: Evaluate:
\[ \log_4 8 + \log_4 2 = \frac{3}{2} + \frac{1}{2} = 2 \]
since $4^{3/2} = 8$ and $4^{1/2} = 2$. The same value comes out in general, so the answer is (B).
Final Answer:
The expression equals 2.
\[ \boxed{2} \]