she was the only one

网友回答

应该是that
she was the only one that was born in 2008 in our country.是定语从句.
先行词是指代人的one,但是one被the only修饰了.
======以下答案可供参考======
供参考答案1:
答案 : WHO
这里指她,是人物,只能用WHO was born. She was the only one who was born in 2008.......
供参考答案2:
B 因为她是人，所以用WHO指代
供参考答案3:
选择B 此句是宾语从句，空格处指的是the only one 是指代人 因此选who
其实选that也可以但是本处who指代性更强