根据短文内容，选择最佳答案。 Once there was a parrot on sale in a pet store. It was a beautiful red and blue bird. It sat on a perch in the middle of the store, so that everyone could see it when they came in. The owner was very proud of it and asked a high price for it.
One day a man went into the store. “That's a beautiful bird,” he said to the pet store owner, “But why is it so expensive? Is it unusual bird?”
“No, it's not very unusual. It's expensive because it can talk,” the pet store owner said.
“I see. How can I make it talk?” the man asked.
The pet store owner asked him, “Do you see those string tied to each of the bird's legs?”
“Yes,”the man answered.
“Well, you pull those strings,” the pet store owner told him. “That will make the parrot talk.”
The man asked, “Do you mind if I try?”
“Not at all,” the pet store owner said.
The man walked up to the parrot and pulled the string on its left leg. The parrot said, “Good morning.”
The man pulled the string on the parrot's right leg. This time the parrot said, “How are you today?”
“That's not very interesting, ” said the man. “Any parrot could do that.” Then he laughed, “But what would happen if I pulled both strings at the same time?”
“I'll fall off my perch, you fool!” the parrot said.
