Which of the following was a problem faced by the average Chinese citizen during the Song dynasty?

Question

a.the shrinking use of the civil service exam and thus the lack of opportunity to obtain a government position
b.the control of the Chinese treasury by northern invaders led to greater taxation
c.an influx of Christian missionaries countering Confucianism
d.overcrowding and health concerns in urban centers
e.greater acceptence of foreigners leading to an erosion of Chinese identity