Final answer:
In 'The Pilgrim's Progress,' the Interpreter suggests that D) the hope of eternal life is the motivational force that propels Christian on his pilgrimage.
Step-by-step explanation:
The Interpreter in John Bunyan's The Pilgrim's Progress advises Christian that D) the hope of eternal life is a good thing that will spur him on his journey.
This concept refers to the inner motivation and the profound desire for an everlasting, blissful existence after death that energizes Christian to continue his pilgrimage, despite the challenges he faces.
This notion aligns with Christian theology and the teachings of Protestantism during the period of the book's writing, particularly emphasizing the significance of spiritual rewards over earthly concerns.