Answer:
A The teacher showed her that history could be approached with imagination.
Explanation:
A
As the title, The Importance of imagination clearly shows, history (and other sciences, for that matter) can, could, and should be approached with imagination.
B is not a wrong statement, but it is not what her high school teacher showed her.
C
A linear or straight-line approach is not exactly what I would call imaginative teaching.
D is, like B, not a wrong statement, but it doesn´t focus at all on the importance of imagination.