Reread this excerpt from "The Pony Express" Chapter 1 and answer the question that follows:

And this great crisis was only the bursting into flame of many smaller fires that had long been smoldering. For generations the two sections had been drifting apart. Since the middle of the seventeenth century, Mason and Dixon's line had been a line of real division separating two inherently distinct portions of the country.

This excerpt introduces the idea that the Civil War was predictable by comparing the events leading up to it to

A. Slow-burning fires

B. Quickly-lit fires

C. Easily-extinguished fires

D. Preventable fires