Answer:
Comparison/contrast.
Step-by-step explanation:
The very opening of the paragraph hints that the expository form that has been employed here by the author is comparison and contrast as it reveals the similar yet distinct character traits of both the writers. The author describes both John Milton and John Bunyan had a hard time and were imprisoned. Despite these difficulties and a life full of adversity they both managed to overcome these hardships and gave birth to excellent art pieces(Milton to the great epic "Paradise Lost" and Bunyan to "The Pilgrim's Progress"). Thus, this exemplifies the comparison and contrasting form of expository structure.