题目内容：
请根据下面短文回答第题： Mara was going to stay with her friend Fanny for three days. A week before her trip, she called Fanny to tell her when the train would arrive. Fanny asked Mara to wait for her at the west entrance ( 入口 ) of the railway station.
The train arrived early. Mara didn't know the station very well and instead of going to the westentrance, she went out of the north entrance and waited for Fanny there.
Fanny checked at the information desk and found that the train had already arrived. She looked round near the west entrance of the station but couldn't see Mara anywhere. She began to think that Mara must have missed the train.
Mara waited at the north entrance, but she couldn't see Fanny. She decided that Fanny was not coming to meet her after all. So she walked across the road to the bus station and asked for the bus to Market Road, where Fanny lived.
You can imagine(想象 ) how surprised Fanny was when she arrived home and found Mara al-ready talking to her mother.
When did Mara tell Fanny about her train ride? A．On the day of her trip.
B．A week before her trip.
C．Three days before her trip.
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答案解析：