Answer:
I'm guessing A? If this is some story, I havent read it before.
Answer:
Pleasing the guards, Doing your work, working hard, and not getting sick or weak.
Explanation:
If you were doing your work you would please the guards and if you weren't sick or weak you wouldnt be killed because you couldnt work anymore. If you were a fit male you would have the most chance of survival.
what caused it was the Japanese army invaded a lot of places so the Japanese govt. became more powerful.
