单项选择题

Christmas Day, the birthday of Jesus Christ, is the most important festival in Britain and some other countries. On Christmas Eve, people usually tell their children to put their stockings at the end of their beds before they go to sleep. Children believe Santa Claus, with the other name of Father Christmas, will come during the night and fill their stockings with Christmas presents.
Aetually(实际上) ,Father Christmas is children"s tather. He dresses up in a red coat and waits until children fall asleep. Then he goes into children"s bedrooms, and puts small presents in their stockings. When children are no longer young, they know who Father Christmas really is.
Not only children but also their parents enjoy Christmas stockings. They also have stockings. Early on the morning of Christmas Day, children wake their parents up and say" MerryChristmas". Then they help their parents open their stockings. Everybody likes presents. But it is better to give than to receive. What is the best greeting(打招呼) early on the morning of Christmas Day in Britain

A.Good luck!
B.Happy New Year!
C.Merry Christmas!