C. Olivia usually refuses to go shopping with her friends because ...

Olivia explains her reluctance to shop alone after her first bad experience. She says: "The truth is, I'm afraid of repeating that bad experience alone." This fear is what makes her hesitate to shop with friends, as she doesn't want to repeat the negative experience on her own, even though she later gains confidence.

Answer: 1. she is afraid of having another bad experience on her own.