How did people in ancient China change their luck? Most of them would take the exam, Keju, which began during the Sui Dynasty and lasted for 1,300 years before it was ended in the Qing Dynasty. Keju, the early "gaokao", played a very important role in choosing qualified persons to work for the king. The Keju exams were mainly based on classical literature  and philo- sophy. Poetry was very important in earlier Keju exams, and later Keju focused more on writing. All _ had to write an article explaining ideas from those books, which was called Eight Part Essay. Two sentences were required at the start of the article, about the main idea of the title, which was called "to clear the topic". The exams also focused on more practical matters. Most candidates in ancient China had to go a long way to the capital city for the exam. As transportation in ancient times was not developed, they usually went to the capital on foot, and some took several months to reach the capital. The exam was held once every three years and it was made up of four levels: the county examination, provincial examination, academy examination and palace examination. Candidates had to first pass one level in order to take part in the next level. Each examination would take from one to three days to finish, and they were locked in a small room and received cold meals. On the exam day, candidates had to first go through safety check. They had to let their hair loose so that it could be checked and their trouser legs, shoes and socks, even bottoms were also checked. Candidates used to walk to the capital because  _  .
they were too poor they didn't have developed transportation they wanted to build up their body they had much time
Question: How did people in ancient China change their luck? Most of them would take the exam, Keju, which began during the Sui Dynasty and lasted for 1,300 years before it was ended in the Qing Dynasty. Keju, the early "gaokao", played a very important role in choosing qualified persons to work for the king. The Keju exams were mainly based on classical literature  and philo- sophy. Poetry was very important in earlier Keju exams, and later Keju focused more on writing. All _ had to write an article explaining ideas from those books, which was called Eight Part Essay. Two sentences were required at the start of the article, about the main idea of the title, which was called "to clear the topic". The exams also focused on more practical matters. Most candidates in ancient China had to go a long way to the capital city for the exam. As transportation in ancient times was not developed, they usually went to the capital on foot, and some took several months to reach the capital. The exam was held once every three years and it was made up of four levels: the county examination, provincial examination, academy examination and palace examination. Candidates had to first pass one level in order to take part in the next level. Each examination would take from one to three days to finish, and they were locked in a small room and received cold meals. On the exam day, candidates had to first go through safety check. They had to let their hair loose so that it could be checked and their trouser legs, shoes and socks, even bottoms were also checked. Candidates used to walk to the capital because  _  .
A. they were too poor
B. they didn't have developed transportation
C. they wanted to build up their body
D. they had much time
Answer: