下列搭配错误的是（　　）

B

    My name is Alice. I have four aunts. They are all great women. Now, let's learn about them.

    This is Emily Smith. She is my father's sister. She is twenty-eight years old. She works at a big computer company.

    This is Rachel Smith. She is my father's sister, too. She is thirty years old. She is a doctor. She takes care of （照顾）patients in a hospital. This is her office. There is a little girl in front her.

    This is Julia King. She is my mother's sister. She is forty-five years old. She is a scientist（科学家）. She works in a lab. It's not big but it's really nice.

    This is Alison King. She is my mother's sister too. She is thirty-two years old. She is a policewoman. Her job is at a police station.

如图，点A、B、C在半径为9的⊙O上， 弧AB的长为2π，则∠ACB的大小是____.