Excerpt from "The Final Assault" from High Adventure by Edmund Hillary I watched our support party disappear down the ridge and then turned to examine our campsite more closely. It wasn’t really much of a place. Above us was a rock cliff—black and craggy, but at least devoid of loose stones to fall on us. From the foot of the cliff a little snow slope ran at an easy angle for eight or nine feet to the top of the steep and exposed South Face of the mountain. This little slope was to be our campsite. It was certainly far from flat and it was to need a lot of work on it before we could possibly pitch a tent. We carefully moved all the gear to one side and then set to work with our ice axes to remove the surface snow off a reasonably large area. Ten inches down, we struck rock, and after an hour’s work we had cleared an area about eight feet long and six feet wide. The slope underneath was made up of stones and rubble all firmly glued together with ice. This was much harder going. With the picks on our ice axes we chopped away at the slope, prizing out the separate stones and scraping away the rubble. But our progress was very slow. We weren’t using any oxygen at all, but we found we could work very hard indeed for periods of ten minutes or so. Then we’d have to stop and have a short rest. 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.

Read these sentences from the "The Final Assault."

This little slope was to be our campsite. It was certainly far from flat and it was to need a lot of work on it before we could possibly pitch a tent. We carefully moved all the gear to one side and then set to work with our ice axes to remove the surface snow off a reasonably large area. Ten inches down, we struck rock, and after an hour’s work we had cleared an area about eight feet long and six feet wide. The slope underneath was made up of stones and rubble all firmly glued together with ice. This was much harder going. With the picks on our ice axes we chopped away at the slope, prizing out the separate stones and scraping away the rubble.

Which phrase best explains why the ideas in these sentences are organized as they are?

to create a chronological account of their work

to explain how to pitch a tent on a mountain

to describe the difficulties of creating a camp

to demonstrate why their actions are important