选A
因为这里是修饰形容词.
so 和 that 不一定要连用,so...that...表示"如此...以至于"
如:He's so poor that he can't afford to buy a bicycle.
so that 表示目的
如:Make some preparations beforehand so that everything will be going smoothly.
such...that 是有的,但是要修饰名词.
如:She's such a nice girl that everybody likes her.
这里的friends前面有形容词few修饰所以选so.