The reason why he took the official government examination at a late age was that             .

Read the passage, and choose the correct answer A, B, C or D for each question.
Nguyen Binh Khiem was a Vietnamese administrator, educator, poet, and sage. As a poet throughout his life, he composed many poems in Chinese and Nom that have survived to this day. He is referred to by several names: Hanh Phu, Bach Van cu si (White Cloud Hermit) and Trang Trinh.
Born in Co Am village in 1491, he got the teaching from the second-rank doctor Luong Dac Bang and passed the official government examination in 1535, ranking number one in the country. This was a period of great instability in Vietnam which may explain the reason why he took the exam at such a late age. He served in the Mac Dynasty court for just seven years until 1542 when he resigned after his official complains about royal court corruptions were ignored. He then returned to his native village and opened a school. Among his students were Phung Khac Khoan (a diplomat), Luong Huu Khanh, Nguyen Du (the author of Truyen ky man luc).
Nguyen Binh Khiem became a person much sought after by many leaders during that time of upheaval, civil war, the Mac collapse, and the rise of the Trinh Lunds and Nguyen Lords. Both Trinh kiem and Nguyen Hoang sought his advice in their pursuit of power. To the former, he gave the advice of being the real power behind the restored Le Dynasty. To the latter, he advised building a base of power in the undeveloped south. Both men followed these suggestions, resulting in a political and military division of Vietnam that would last for 200 years. As a result of this sage advice, Nguyen Binh Khiem gained a reputation as someone who could foretell the future. Some of his prophecies were of a Delphic nature as they were ambiguous and could be read in several ways.

Choose the correct answer