阅读下面材料，然后从各题所给的四个选项中选出一个最佳答案。
Mr. King is the manager (经理) of
a hotel. One day all of the hotels in the city are full because there is a
large meeting. In the evening, three men come into the hotel and ask for rooms.
Mr. King says there are no rooms because of the meeting. The men are unhappy.
Mr. King wants to help them. He remembers
that Room 418, a very small room is empty. He asks them if they would share (分享) a
room. The three men says yes. Mr. King says the room would be thirty dollars, ten
for each one (每一个). Each man gives him the money and
then they go up to the room.
Mr. King soon begins to feel sorry. The
price is too high for that small room, he thinks. He says to his assistant (助手),
Here is five dollars. Take the money to the men in Room 418. I ask too much for
their room.
The assistant takes the money. While she is
on the way there, she starts to think, "How can three men divide (分配)
five dollars? So the assistant returns (还) one dollar
to each man and she keeps the two dollars for herself.
Each man pays ten dollars at first. After
the assistant returns them one dollar each, each pay nine. There are three men.
So $9x3= $27. The assistant keeps $2. $27 + $2= $29. Where is the missing (消失的) dollar?
