David is eight. One day his friend Rose says to him, "This Sunday is my birthday. Can you come to my birthday party?" David says, "Yes". On Sunday, David asks his mother if he can go to the party. His mother says, "Yes, you can go, but you must be polite. Don't ask for any food. They will give you some." "All right, Mum." David answers and he goes to Rose's house on his bike. There are lots of kids at the party. They play together for some time, and then Rose's mother gives them some food, but she forgets David. He waits and waits and then he takes his plate up and asks, "Do you want a nice clean plate?" David is Rose's   _  .
mother classmate brother friend