Final answer:
Augustus proposing a trip to Amsterdam to meet Peter Van Houten in 'The Fault in Our Stars' is an instance of foreshadowing their future journey. Option number a is correct.
Step-by-step explanation:
The question pertains to the concept of foreshadowing, a literary device where an author provides hints about future plot developments. In 'The Fault in Our Stars,' when Augustus talks about arranging to meet Peter Van Houten by visiting Amsterdam rather than waiting for something to happen, it serves as an instance of foreshadowing.
This moment hints at the impending journey they will undertake to seek answers from the author. It is an example of the narrative laying the groundwork for future events that the readers will encounter, similarly to how foreshadowing functions in classic literature, such as in 'Antigone' or Shakespeare's plays.