The correct answer is: He uses unjust treatment of Sampson by the Philistines to draw attention to the plight of prisoners throughout history.
The author describes both Sampson's and the slave's plights in the story - the slave being discussed in the first two paragraphs, and Sampson being introduced at the last one. Moreover, both these two characters' conditions are presented in a similar manner: They are poor, blind and have been shorn of their strenghts - with Sampson being additionally eager to break his bonds.
The slave in the story is a poetic description of the suffering of every prisoner that has ever existed, and Sampson is included in this characterization as to highlight the prisoner's desire to escape.
she wanted to be the first woman to be in the army for a long time and she said she would be in the same boat as her mother if she had been growing up with the family of the right 7