To simplify the expression \((xy)^8\), let's break it down step by step:
1. Start with the given expression: \((xy)^8\).
2. According to the exponentiation rule \((a \cdot b)^c = a^c \cdot b^c\), we can apply the exponent 8 to both \(x\) and \(y\) individually.
3. Therefore, \((xy)^8\) simplifies to \(x^8 \cdot y^8\).
So, the simplified form of the expression \((xy)^8\) is:
[tex]\[
\boxed{x^8 y^8}
\][/tex]
Hence, the correct answer is B. [tex]\(x^8 y^8\)[/tex].
