阅读下列短文，然后根据短文的内容从 51～54 小题的四个选择项中选出最佳的一项。
A
There was a river with a small town on either side of it. The towns were linked by a bridge.
One day，a hole appeared in the bridge. Both towns agreed that the hole should be mended. However，disagreement came up as to who should mend it. Each town thought that it had a better reason for the other to mend the hole. The town on the right bank said that it was at the end of the road，so the left-bank town should mend the hole. The town on the left bank，on the other hand，insisted that all the traffic came to the right-bank town，so it was in their interest to mend the bridge.
The quarrel went on and on，and so did the hole. The more it went on，the more the hostility between the two towns grew.
One day a man fell into the hole and broke his leg. People from both towns questioned him closely about whether he was walking from the right bank to the left or from the left bank to the right，in order to decide which town should be blamed for the accident. But he could not remember，since he got drunk that night.
Some time later，a car was crossing the bridge and broke an axle（轴）because of the hole. Neither town paid any attention to the accident，as the traveler was not going from one to the other，but was merely passing through. The angry traveler got out of the car and asked why the hole was not mended.
On hearing the reason，he declared，“I'll buy this hole. Who‘s the owner？”
Both towns at once declared that they owned the hole.
“One or the other，whoever owns the hole must prove it.”
“How shall we prove it？”asked both sides.
“That's simple. Only the owner of the hole has the right to mend it. I‘ll buy the hole from whoever mends the bridge.”
People from both towns rushed to do the job while the traveler smoked a cigar and his driver changed the axle. They mended the bridge in no time and asked for the money for the hole.
“What hole？”The traveler looked surprised.“I can't see any hole. I‘ve been looking for a hole for several years now. I'm prepared to pay a good price for it，but there’s no hole here. Are you pulling my leg or what？”
He got into his car and drove off.
第 51 题 What did the two towns quarrel about？

A. Which of them should mend the hole.
B. Whether the hole should be mended.
C. Why there was a hole in the bridge.
D. When they should mend the hole.