Question

This is the room whose windows open to ___ south.

A.the B.a C.an D./
应该选哪一个，为什么？

Answer 1

应该选A. This is the room whose windows open to the south. 这件房子的窗户面朝南核侍。
此处的south是名词，the south “南方，南部"，属于固定用法。上个句子也可以改塌吵这样讲：
This is the room whose windows faces south. 此处的south是形容词，表示“衫蚂向南，朝南”，作为动词face的宾语。句式结构可以不用理解的这么透彻。

Answer 2

选A 特指窗户向南方开的！

Answer 3

A 固定用法