听力原文： When I was in the third grade, I was picked to be the princess in the school play. For weeks my mother had helped me practice my lines. But once on stage, every word disappeared from my head. Then my teacher told me she bad written a narrator's part for the play, and asked me to change roles. Though I didn't tell my mother what had happened that day, she sensed my unhappiness and asked if I wanted to take a Walk in the yard.
It was a lovely spring day. We could see dandelions popping through the grass in bunches, as if a painter had touched our landscape with bits of gold. I watched my mother carelessly bend down by one of the bunches. "I think I am going to dig up all these weeds," she said. "From now on, we'll have only roses in this garden. "
"But I like dandelions," I protested. "All flowers are beautiful — even dandelions!" My mother looked at me seriously. "Yes, every flower gives pleasure in its own way, doesn't it？" she asked thoughtfully. I nodded. "And that is true of people, too," she added.
When I realized that she had guessed my pain, I started to cry and told her the truth.
"But you will be a beautiful narrator," she said, reminding me of how much I loved to read stories aloud to her.
Over the next few weeks, with her continuous encouragement, I learned to take pride in the role. The big day finally came. A few minutes before the play, my teacher came over to me. "Your mother asked me to give this to you," she said, handing me a dandelion. After the play, I took home the flower, laughing that I was perhaps the only person who would keep such a weed.
(30)

A. Mainly because she felt nervous on the stage.
B. Mainly because she lost her interest in that role.
C. Mainly because she preferred the role of the narrator.
D. Mainly because she had difficulty memorizing her words.