excerpts from "The Final Assault" from High Adventure by Edmund Hillary

At 6:30 a.m. we crawled slowly out of the tent and stood on our little ledge. Already the upper part of the mountain was bathed in sunlight. It looked warm and inviting, but our ledge was dark and cold. We lifted our oxygen onto our backs and slowly connected up the tubes to our face masks. My thirty-pound load seemed to crush me downward and stifled all enthusiasm, but when I turned on the oxygen and breathed it deeply, the burden seemed to lighten and the old urge to get to grips with the mountain came back. We strapped on our crampons and tied on our nylon rope, grasped our ice axes, and were ready to go…

“What do you think of it Tenzing?” And the immediate response, “Very bad, very dangerous!” “Do you think we should go on?” and there came the familiar reply that never helped you much but never let you down: “Just as you wish!” I waved him on to take a turn at leading. Changing the lead much more frequently now, we made our unhappy way upward, sometimes sliding back and wiping out half a dozen steps and never feeling confident that at any moment the whole slope might not avalanche. In the hope of some sort of a belay we traversed a little toward the rocks but found no help in their smooth holdless surface. We plunged on then upward. And then I noticed that, a little above us, the left-hand rock ridge turned into snow and the snow looked firm and safe. Laboriously and carefully we climbed across some steep rock and I sank my ice ax shaft into the snow of the ridge. It went firm and hard. The pleasure of this safe belay after all the uncertainty below was like a reprieve to a condemned man. Strength flowed into my limbs and I could feel my tense nerves and muscles relaxing. I swung my ice ax at the slope and started chipping a line of steps upward—it was very steep but seemed so gloriously safe. Tenzing, an inexpert but enthusiastic step cutter, took a turn and chopped a haphazard line of steps up another pitch. We were making fast time now and the slope was starting to ease off. Tenzing gallantly waved me through and with a growing feeling of excitement I cramponed up some firm slopes to the rounded top of the South Summit. It was only 9 a.m.

It was 11:30 a.m. My first sensation was one of relief—relief that the long grind was over; that the summit had been reached before our oxygen supplies had dropped to a critical level; and relief that in the end the mountain had been kind to us in having a pleasantly rounded cone for its summit instead of a fearsome and unapproachable cornice. But mixed with the relief was a vague sense of astonishment that I could have been the lucky one to attain the ambition of so many brave and determined climbers. It seemed difficult at first to grasp that we’d got there. I was too tired and too conscious of the long way down to safety really to feel any great elation. But as the fact of our success thrust itself more clearly into my mind I felt a quiet glow of satisfaction spread through my body—a satisfaction less vociferous but more powerful than I had ever felt on a mountaintop before. I turned and looked at Tenzing. Even beneath his oxygen mask and the icicles hanging from his hair I could see his infectious grin of sheer delight.

Question
Read these sentences from "The Final Assault."

At 6:30 a.m. we crawled slowly out of the tent and stood on our little ledge. Already the upper part of the mountain was bathed in sunlight...

Tenzing gallantly waved me through and with a growing feeling of excitement I cramponed up some firm slopes to the rounded top of the South Summit. It was only 9 a.m....

It was 11:30 a.m. My first sensation was one of relief—relief that the long grind was over; that the summit had been reached before our oxygen supplies had dropped to a critical level; and relief that in the end the mountain had been kind to us in having a pleasantly rounded cone for its summit instead of a fearsome and unapproachable cornice...

Why does Hillary include time as a way to organize these paragraphs about reaching the summit of Mt. Everest?

Responses

to stress the idea that keeping track of hours is important to mountain climbers
to stress the idea that keeping track of hours is important to mountain climbers

to show how long it took to complete the final climb to reach the summit
to show how long it took to complete the final climb to reach the summit

to relate how quickly experienced climbers could climb the difficult peak
to relate how quickly experienced climbers could climb the difficult peak

to express the idea that it is difficult to climb during the morning hours
to express the idea that it is difficult to climb during the morning hours

The correct response is:

to show how long it took to complete the final climb to reach the summit