Read this excerpt from “The Final Assault” by Sir Edmund Hillary. With the debris we chopped out of the slope we tried to build up the platform on the downhill side, but almost invariably saw it collapse and go roaring down over the bluffs below. At times we were buffeted by wind and snow, yet we worked doggedly on, knowing that our tent was our only chance of survival against the rigors of the night. Which statement best describes the author’s purpose in this excerpt?