Final answer:
The rioters in St. Petersburg likely appealed to the soldiers to cease fire, as it is consistent with the historical behavior of protesters seeking to minimize the violence during uprisings.
Step-by-step explanation:
In the context of historical events, when rioters in St. Petersburg appealed to the soldiers, they were likely looking for some form of reprieve or assistance in the face of aggression or potentially lethal force. Given the descriptions provided in various historical contexts, the most fitting answer among the provided options would be a) To cease fire. Typically, in historical uprisings or protests where there is a threat of violence, appeals to soldiers would be aimed at reducing violence or seeking protection.
When considering the provided historical references, it's clear that the rioters' appeal to the soldiers would not be for reinforcements (as the soldiers would act against them), for amnesty (which would be a political decision beyond the soldiers' authority), or for negotiations (which would not typically happen in the heat of a conflict but rather afterwards). Therefore, the appeal to cease fire aligns with the historical behavior of protesters seeking to minimize violence.