It was originally built to defend an empire ,but now parts of the Great Wall of China are crumbling  so badly they need someone to hurry to their defense. About 2,000 kilometers, or 30%,of the ancient fortification  built in the Ming Dynasty has disappeared due to natural and human damage, according to the Beijing Times. And the situation could worsen, experts are warning as not enough is being done to preserve what remains. "It's a great pity to witness the Great Wall in such terrible situation ," Mei Jingtian, a volunteer who has worked for three decades to safeguard the structure and has founded the Great Wall Protection Association, tells CNN. About 8,000 kilometers of the structure dates from the Ming period between the 14th and 17th centuries and is considered by some to be the original Great Wall.Of this, 2,000 kilometers is made up of naturally occurring earthworks - and so only 6,000 kilometers of actual Ming dynasty wall was ever built.  Stretches built in other eras make up a total length estimated up to 21,000 kilometers. Many visitors to china associate the Great Wall with a widely restored stretch of Ming era wall at Badaling near Beijing, but this is far from typical of most of the structure. According to a 2014 survey done by the Great Wall of China Society, only about 8.2% of the Great Wall is in good condition, with74. 1% classified as poorly preserved, "The Great Wall is a vast heritage site - over 20,000 kilometers - thus increasing the difficulty in preservation and restoration," Dong Yaohui, deputy director of the Great Wall of China Society, tells CNN. "Reliance on a very small amount of manpower by the local heritage departments is not enough to guard and protect the site." A recent increase in interest from tourists in visiting wild sections, known as the "Wild Great Wall," has Accelerated its deterioration ,according to the report. The present situation of the Great Wall is not optimistic due to the following reasons EXCEPT  _  .
natural and human damage limited preservation booming tourists visiting wars between countries
Question: It was originally built to defend an empire ,but now parts of the Great Wall of China are crumbling  so badly they need someone to hurry to their defense. About 2,000 kilometers, or 30%,of the ancient fortification  built in the Ming Dynasty has disappeared due to natural and human damage, according to the Beijing Times. And the situation could worsen, experts are warning as not enough is being done to preserve what remains. "It's a great pity to witness the Great Wall in such terrible situation ," Mei Jingtian, a volunteer who has worked for three decades to safeguard the structure and has founded the Great Wall Protection Association, tells CNN. About 8,000 kilometers of the structure dates from the Ming period between the 14th and 17th centuries and is considered by some to be the original Great Wall.Of this, 2,000 kilometers is made up of naturally occurring earthworks - and so only 6,000 kilometers of actual Ming dynasty wall was ever built.  Stretches built in other eras make up a total length estimated up to 21,000 kilometers. Many visitors to china associate the Great Wall with a widely restored stretch of Ming era wall at Badaling near Beijing, but this is far from typical of most of the structure. According to a 2014 survey done by the Great Wall of China Society, only about 8.2% of the Great Wall is in good condition, with74. 1% classified as poorly preserved, "The Great Wall is a vast heritage site - over 20,000 kilometers - thus increasing the difficulty in preservation and restoration," Dong Yaohui, deputy director of the Great Wall of China Society, tells CNN. "Reliance on a very small amount of manpower by the local heritage departments is not enough to guard and protect the site." A recent increase in interest from tourists in visiting wild sections, known as the "Wild Great Wall," has Accelerated its deterioration ,according to the report. The present situation of the Great Wall is not optimistic due to the following reasons EXCEPT  _  .
A. natural and human damage
B. limited preservation
C. booming tourists visiting
D. wars between countries
Answer: