The kite was originally called Zhiyuan in North China, and Yaozi in South China. Early in the Five dynasties, a man named Li Ye used to make and fly a kite in the emperor's court. He once attached a whistle made of bamboo to the kite. Sound was let out when the kite was flying. The kite was named after  Zheng, a kind of Chinese music instrument. Then it was named Fengzheng in Chinese. The earliest kite in the world was made by Motse, a famous Chinese philosopher, who lived 2,300 years ago, for military   purposes. He spent three years making an eagle and managed to fly it. The eagle was later regarded as the first kite in the world. Kite-flying became a recreation probably from the Tang dynasty when the royal family and people of the highest class were addicted to it. It was said that the Emperor Xuanzong in the Tang Dynasty once was interested in a kite named Eight Immortals Crossing the Sea flying in the air. Later, the paper-made kite was invented, which cost less and spread quickly among the common people. As time went on, kites flew to various countries in the world. 'The well-known British scientist, Dr. Needham, once described kites as an important scientific invention which spread to Europe from China in his book, A History of China's Science and Technology. The invention of the kite inspired men's dream of flying and led to the invention of the airplane. Why was kite-flying not a popular recreation among common people at first?
Because they were too busy to fly kites. Because they were not allowed to fly kites. Because it was difficult to make kites. Because it was expensive to make kites.
Question: The kite was originally called Zhiyuan in North China, and Yaozi in South China. Early in the Five dynasties, a man named Li Ye used to make and fly a kite in the emperor's court. He once attached a whistle made of bamboo to the kite. Sound was let out when the kite was flying. The kite was named after  Zheng, a kind of Chinese music instrument. Then it was named Fengzheng in Chinese. The earliest kite in the world was made by Motse, a famous Chinese philosopher, who lived 2,300 years ago, for military   purposes. He spent three years making an eagle and managed to fly it. The eagle was later regarded as the first kite in the world. Kite-flying became a recreation probably from the Tang dynasty when the royal family and people of the highest class were addicted to it. It was said that the Emperor Xuanzong in the Tang Dynasty once was interested in a kite named Eight Immortals Crossing the Sea flying in the air. Later, the paper-made kite was invented, which cost less and spread quickly among the common people. As time went on, kites flew to various countries in the world. 'The well-known British scientist, Dr. Needham, once described kites as an important scientific invention which spread to Europe from China in his book, A History of China's Science and Technology. The invention of the kite inspired men's dream of flying and led to the invention of the airplane. Why was kite-flying not a popular recreation among common people at first?
A. Because they were too busy to fly kites.
B. Because they were not allowed to fly kites.
C. Because it was difficult to make kites.
D. Because it was expensive to make kites.
Answer: