To begin playing a certain card game, an ordinary deck of playing cards is dealt out completely to four players. Each player looks at his cards and passes one card to the person on his left. A player does not look at the card passed to him until he has passed a card. If a player has more than one king, he must pass a king; if has only one king, he may not pass it. How many rounds of passing are necessary to ensure that each player has one king?

A. 3       B. 4       C. 5       D. 6       E. 7