下面程序的运行结果是（ ）public static void main(String[] args){ String s1 = "abc"; String s2 = "xyz"; show(s1,s2); System.out.println(s1+"-----"+s2);}static void show(String s1,String s2){ s1 = s2+s1+"Q"; s2 = "W"+s1;}
选项：

A:abc-----xyz
B:abc_xy
C:abc+xy
D:abcxy