有定义语句：int a=1,b=2,c=3,x;，则以下选项中各程序段执行后，x的值不为3的是

A．if (c＜a) x=1;else if (b＜a) x=2;else x=3;
B．if (a＜3) x=3;else if (b＜a) x=2;else x=1;
C．if (a<3) x=3;if (a<2) x=2;if (a<1) x=1;
D．if (a＜b) x=b;if (b＜c) x=c;if (c＜a) x=a;