You may know the song Happy Birthday very well.But do you know about its writer?It was written by an American girl.And she became very rich after that. When she was a child,she was poor.Once,she was invited to her friend's birthday party.She was pleased but sad because she didn't have enough money to buy a gift for her. "The party is coming soon,but now I have little money."Tears ran down her face. Later that night she was in bed,thinking about the gift when the door opened and her grandma came in."What happened?"her grandma asked.Hearing the girl'story,she said,"I think I can help you.How about singing a song together?Happy Birthday to...."What a beautiful song!They sang and sang.Suddenly she woke up.It was a dream!She decided to write it down at once and sing it to her friends at the party. When she sang the song at the party the nest day,her friends were very happy."How wonderful you sing!We haven't heared such a beautiful song before.Thank you for giving me the special gift."said her friend.And they learn to sing it together.Later the girl became well-known in America. The song Happy Birthday was written by  _  .
an American girl an American girl's grandma an America boy an American girl's friend