Final answer:
Poverty unites the suffering in The Mark by Edyth Bulbring by fostering a sense of solidarity in suffering.
Step-by-step explanation:
Poverty unites the suffering in The Mark by Edyth Bulbring by fostering a sense of solidarity in suffering (Option C). The characters in the novel who experience poverty are able to connect with one another through their shared struggles and hardships. This creates a bond among them and allows them to support each other in the face of adversity.