答案：C of which
解析：如果用the windows 则用of which
如果windows 用在横线后面,则使用whose
注意：
she decided to buy the house ,the windows【of which】faced the blue sea
she decided to buy the house ,【whose windows】faced the blue sea
无疑后请采纳.
书山有路勤为径,学海无涯苦作舟.
-----------与君共勉-----------