Grandfather Summers Had Two Children,Mary and Bill

Grandfather Summers had two children,Mary and Bill.Mary,her father's favorite,has one child,Margaret.Bill has two children,Jill and John.Mary and Bill die before Summers (in legal terms,predecease him) ,but all three grandchildren are living at the time of his death.Summers' estate has to be divided per capita.Who will get what?

A) The spouses of Mary and Bill will inherit the estate.
B) Mary's children will inherit the major share of the estate.
C) All three grandchildren will get an equal share.
D) The estate will go to a trust because Mary and Bill are dead.