单项选择题

Passage Four
Many tourists must have dreamed of owning a small house in a foreign country -- perhaps on a stretch of lonely coast -- to which they could return year after year to enjoy the sun and the sea. Others, with even bigger ideas and a lot more money to spend, think of buying hotels. In any case, it is absolutely essential to know a great deal about the value of property, otherwise the buyer may be at the mercy of(由……摆布) dishonest agents.
Some tourists, however, are so foolish that they really deserve to be cheated by agents. We would consider a person mad if he walked into a museum and asked to "buy" a great work of art. Though no one has told us, we all know that certain things can never be sold, no matter how much money is offered. Yet, nearly every year since 1944, a buyer has been found for the Colosseum (古罗马圆形剧场) in Rome. The first one was a soldier who parted with his money for what was described as "a rather broken down and heavily damaged building in a good position".
The people of Rome eagerly look forward to each year’s "sale". They were amused to learn that, as usual, a tourist recently expressed the desire to buy the historic building. Two agents told him that the building was in need of repair, but the buyer could expect a high return for his capital. They took him to the Colosseum itself and pointed out that the top floor would make a wonderful international restaurant.
It was in an ideal position and offered a fine view of the city of Rome. Besides, for some strange reason, so many people wished to visit the building that the buyer would make a considerable profit on entrance tickets. In the agents’ opinion, it was well worth spending money on a building like this. They asked the buyer for a mere 200 000 lire as a deposit and told him they would complete arrangements that evening at a certain hotel. The tourist was sure that he had bought ’a bargain and later went to the hotel to meet the agents. But, of course, they never came.
"The buyer may be at the mercy of dishonest agents" (Para. 1) most probably means that ______.

A.dishonest agents are merciful to the buyer
B.dishonest agents are merciless to the buyer
C.the buyer may be completely controlled by the dishonest agents
D.the buyer may have pity on the dishonest agents