Read the passage from the acknowledgements.

The idea for this book began to take shape more than six years ago when I came across a copy of John H. Powell’s Bring Out Your Dead. Reading this book was a revelation, not just because of the depth of scholarship, but because Powell brought the time alive in a powerful and emotional way. I’ve discovered that no one writes about the Philadelphia epidemic—no one writes about yellow fever, period!—without relying heavily on this work, and that includes me.

–An American Plague,
Jim Murphy

What information about the text does this passage provide?

It explains the wide range of sources the author used.
It rouses the reader’s interest in the subject through description.
It suggests that the author has found a particular source very useful.
It compares and contrasts the author’s views with those of other authors.