Which of the following statements is true regarding the chinese civil service exams?
a. they were open to all males regardless of age or social class and included district, provincial, and metropolitan levels
b. they included a written, oral, and performance element in addition to public testimony
c. they were based on confucian, daoist, and buddhist teachings and demanded candidates be able to discuss all elements of the three philosophies
d. they were restricted to family members of existing civil servants as a means of maintaining social stability