Prof. Hernandez's monumental work The History of Central America cover

Magoosh Official Explanation

This argument has the form: evidence, evidence, evidence, and then all of a sudden … BAM! This book is not a history book. The author must have a strong assumption about what constitutes the discipline of history. In particular, most of the paragraph is about how Prof. Hernandez book contains more theory and fewer facts, and this appears to be the grounds for the judgment. Therefore, we need an assumption that connects a focus on facts to the definition of history.

(D) is the credited response. If it were true that history is concerned only with facts, not theories, this would explain why Prof. Hernandez's theory-heavy book is not a history book. This is the correct assumption. (BTW, outside of this particular question, this is definitely NOT the general assumption in the field if history itself. It sound very much like Prof. Hernandez, and not the author of this argument, really understands how modern historical studies operate.)

(A) and (B) both leave open a variety of interpretations about what constitutes history, so both would allow for classifying Prof. Hernandez's book as a history book.

(C) is more a recommendation than an assumption, and it appears to favor a theoretical approach, which apparently is precisely what the author of this argument finds problematic about Prof. Hernandez's book.

(E) is irrelevant --- it picks up on one small detail of the prompt, and does not address the main issue: what constitutes history as a discipline?