Which Man class properly represents the relationship "Man has a best friend who is a Dog"?（）
- Aclass Man extends Dog { }
- Bclass Man implements Dog { }
- Cclass Man { private BestFriend dog; }
- Dclass Man { private Dog bestFriend; }
- Eclass Man { private Dog<bestFriend>; }
- Fclass Man { private BestFriend<dog>; }