|x & a & ... & a a & x & ... & a vdots & vdots & ddots & vdots a & a & ... & x

$\left|\begin{array}{cccccc}x & a & \cdots & a \\ a & x & \cdots & a \\ \vdots & \vdots & \ddots & \vdots \\ a & a & \cdots & x\end{array}\right| = \_\_\_$。

A. $[(n-1)a+x](x-a)^{n-1}$

B. $(na+x)(x-a)^{n-1}$

C. $[(n+1)a+x](x-a)^{n-1}$

D. $[(n+2)a+x](x-a)^{n-1}$