Simplify the expression. \[ \frac{x-8}{8-x} \] Select the correct choice below and fill in any answer boxes in your choice. A. $\frac{x-8}{8-x}=\square$ B. The expression cannot be simplified.

Step 1 ：Given the expression \(\frac{x-8}{8-x}\).

Step 2 ：Factor out a negative one from the denominator to change the sign of the denominator and make it identical to the numerator.

Step 3 ：This simplifies the expression to -1.

Step 4 ：Final Answer: \(\boxed{-1}\)