bcz there must be only 3 person ..that is grandfather and his son ..and his 1 grandchild who is the son of grandfather\'s son .... hence 1 grandfather .his son and 1 grand son
bcz there must be only 3 person ..that is grandfather and his son ..and his 1 grandchild who is the son of grandfather's son .... hence 1 grandfather .his son and 1 grand son
in 2 sons , one is the son of grandfather i.e the father itself. other is fathers son. there for there is 3 cups 1 for grandfather 2 for father and 3 for his son.
in 2 sons , one is the son of grandfather i.e the father itself. other is fathers son. there for there is 3 cups 1 for grandfather 2 for father and 3 for his son.
father' s father and father' s son
there are only three persons