Final answer:
The literary element used in the given statement is Theme. Theme refers to the underlying message or main idea that the author wants to convey through a story.
Step-by-step explanation:
The literary element used in the given statement is Theme. Theme refers to the underlying message or main idea that the author wants to convey through a story. In this case, the theme is indicated by the student's mother saying that the book was 'so easy to read', implying that the student's writing was clear and accessible.