I think is Because Christians refused to worship the Roman gods. It will help you :)
Answer:
Agricultural yields were about 2 tan (a unit of about 110 pounds or 50 kilograms) of grain per mu during the Song dynasty, compared with 1 tan during the early Han and 1.5 tan during the late Tang.
Explanation:
I just took the Penn Foster exam. The answer is C. Better Transportation
I hope this helps! :D