David;s brother gave him a big yellow box. David opened it and there was another box in it. The box was green. He opened the small box ans saw the third box. This one was blue. There was a short letter in it. "Go to your study. You can see three boxes there, a a black one, a grey oneanda white one. Your birthday present is in one of them." David ran to to his study and found them on the desk. The black one is bigger than the grey one, and the white one is the smallest. He opened the grey box., but found nothing in it.Then he opened the biggest one. He was very glad to seee a model plane in it.
How many boxes did David' s brother give him?
A. 4 B. 5 C. 6 D. 7