Answer:
B. The setting is the era of slavery, which leads to Jim's need to escape.
Explanation:
According to the synopsis, the statement that best explains how the setting affects the plot of The Adventures of Huckleberry Finn is the setting is based on the slave trade era which prompts Jim's need for emancipation.
Jim is a slave, while Huck is also pushed by the need to be mentally free from the shackles society puts on him.