The correct answer is Being forced to stand in the hot sun, enduring beatings, catching diseases, and getting shot.
Japanese didn't do this, this was done by Germans. Japanese made them relocate and undergo the march and if they didn't want to they'd get beaten or they would be killed. The diseases spread rapidly because of the state the people were in and they suffered from things like dysentery. Sitting and standing in the hot sun without shade was a common method of torture at the time.
