December 25 is Christmas Day . Christmas is an important holiday in many countries. On Christmas Day, most families get together for a big dinner. They give presents to each other and visit friends. The Christmas tree is an important part of the Christmas holiday. Most families buy trees. The families decorate  the tree together. Parents usually tell their children that Father Christmas comes during the night and brings presents to good children. Of course, Father Christmas isn't real. The parents of the children are really "Father Christmas". They put the presents under the tree or into their children's stocking  after the children go to sleep. Who is really "Father Christmas"?   _  .
Their parents Their father Their mother Father Christmas