C语言程序设计章节练习四：选择结构

当a = 1, b = 3, c = 5, d = 4时，执行完下面程序段后x的值为（　　）。

if (a < b)
if (c < d) x = 1;
else
if (a < c)
if (b < d) x = 2;
else x = 3;
else x = 6;
else x = 7;