When it comes to cultural heritage protection, the Grand Canal of China is probably the world's greatest project of its kind.  The big inland waterway system in the north-eastern and central eastern plains passes through eight of the country's present-day provinces. The Canal runs from Beijing in the north to Zhejiang Province in the south. Constructed in sections from the 5th century BC onwards, it was designed as a means of communication in the 7th century AD.  The Canal is the world's greatest civil engineering project before the Industrial Revolution. The Grand Canal reached a peak in the 13th century, providing an inland navigation  network consisting of more than 2,000 kilometers of artificial waterways, linking five of the most important river basins in China, including the Yellow River and the Yangtze. It entered a bid as a UNESCO  cultural heritage site in 2008. The Grand Canal cultural square is located in Beijing's Tongzhou district. Ever since the Yuan dynasty 800 years ago, the Tongzhou section of the Grand Canal has been the life blood of Beijing. Grain and building materials were all transported to meet the endless demands of the big cities. Even today, the Grand Canal plays a major role in the lives of its citizens. "I grew up near the Grand Canal. In the past the waterway was a lot narrower, but now it's nice and wide and bridges are built over it. I think if the bid for world heritage status succeeds, it will greatly make Tongzhou more famous in the world, especially with Tongzhou aiming to be a sub-center of the capital Beijing," a citizen said. The result of the bid is set to be released next week, and no doubt it will certainly make it into the history books if the Canal is listed as a world heritage site. The Grand Canal was in the most glorious time  _  .
when it was aimed as a means of communication when it crossed the Yellow River and the Yangtze when it was born about six hundred years later when it was designed as an artificial waterway
Question: When it comes to cultural heritage protection, the Grand Canal of China is probably the world's greatest project of its kind.  The big inland waterway system in the north-eastern and central eastern plains passes through eight of the country's present-day provinces. The Canal runs from Beijing in the north to Zhejiang Province in the south. Constructed in sections from the 5th century BC onwards, it was designed as a means of communication in the 7th century AD.  The Canal is the world's greatest civil engineering project before the Industrial Revolution. The Grand Canal reached a peak in the 13th century, providing an inland navigation  network consisting of more than 2,000 kilometers of artificial waterways, linking five of the most important river basins in China, including the Yellow River and the Yangtze. It entered a bid as a UNESCO  cultural heritage site in 2008. The Grand Canal cultural square is located in Beijing's Tongzhou district. Ever since the Yuan dynasty 800 years ago, the Tongzhou section of the Grand Canal has been the life blood of Beijing. Grain and building materials were all transported to meet the endless demands of the big cities. Even today, the Grand Canal plays a major role in the lives of its citizens. "I grew up near the Grand Canal. In the past the waterway was a lot narrower, but now it's nice and wide and bridges are built over it. I think if the bid for world heritage status succeeds, it will greatly make Tongzhou more famous in the world, especially with Tongzhou aiming to be a sub-center of the capital Beijing," a citizen said. The result of the bid is set to be released next week, and no doubt it will certainly make it into the history books if the Canal is listed as a world heritage site. The Grand Canal was in the most glorious time  _  .
A. when it was aimed as a means of communication
B. when it crossed the Yellow River and the Yangtze
C. when it was born about six hundred years later
D. when it was designed as an artificial waterway
Answer: