Final answer:
A character study provides an in-depth look into a character's evolution over time. In the provided choices, the option 'a book about how Harry Potter changed throughout the series' matches this definition by allowing for a deep analysis of Harry Potter's development over the series.
Step-by-step explanation:
In an examination of the choices given, the one that is most likely a character study would be "d. a book about how Harry Potter changed throughout the series". A character study takes a deep look into the changes in a character's traits, behaviors, and relationships over the narrative's course, providing an in-depth analysis of that character's development. In this example, the book would be studying the evolution of Harry Potter from a young wizard to an experienced and scarred hero, demonstrating the change in his character over the duration of the series.
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