单选题：请根据短文内容，回答题。Narrow EscapeWe had left the hut too late that m

请根据短文内容，回答题。
Narrow Escape
We had left the hut too late that morning. When we stepped outside, the sky beyond the mountains to our east was already livid with colour. It meant the day would be a hot one, and the warmth would loosen rocks that were gripped by ice.
As soon as we stepped out on to the face, it became obvious this was going to be an awkward route. The main problem was talus, the debris that collects on mountainsides. Talus is despised by mountaineers for two reasons. First, because it can easily be pushed off on to you by people climbing above. And second, because it makes every step you take insecure.
For about 30 minutes we moved steadily up the face. The rock was in poor condition. When I tried to haul myself up on a block of it, it would pull towards me, like a drawer opening. My hands became progressively wetter and colder. Then came a shout. "Cailloux! Cailloux!" I heard, yelled from above, in a female voice. The words echoed down towards us. I looked up to see where they had come from.
There were just two rocks at first, leaping and bounding down the face towards us, once cannoning off each other in mid-air. And then the air above suddenly seemed alive with falling rocks, humming through the air and filling it with noise. Crack, went each one S it leapt off the rock face, then hum-humhum as it moved through the air, then crack again. The pause between the cracks lengthened each time, as the rocks jumped further and further. I continued to gaze up at the rocks as they fell and skipped towards me. A boy who had been a few years above me at school had taught me never to look up during a rock fall. "Why? Because a rock in your face is far less pleasant than a rock on your helmet," he told us. "Face in, always face in."
i heard Toby, my partner on the mountain that day, shouting at me. I looked across, he was safe beneath an overhanging canopy of rock. I could not understand him. Then I felt a thump, and was tugged backwards and round, as though somebody had clamped a heavy hand on my shoulder and turned me to face them. A rock had hit the lid of my rucksack.
I looked up again. A rock was heading down straight towards me. Instinctively, I leant backwards and arched my back out from the rock to try to protect my chest. What bout my fingers,though, I thought: they' 11 be crushed fiat if it hits them, and never get down. Then I heard a crack directly in front of me, and a tug at my trousers; and a yell from Toby. "Are you all right? That went straight through you." The rock had passed through the hoop of my body, between my legs,missing me but snatching at my clothing as it went.
Toby and I spent the evening talking through the events of the morning: what if the big final stone hadn't leapt sideways, what if I'd been knocked off, would I have held me, would I have pulled you off? A more experienced mountaineer would probably have thought nothing of it. I knew I would not forget it.
Why was it "too late" by the time they left the hut in the morning? A．It would be uncomfortable climbing in hot weather.
B．The livid colour of the sky would hurt their eyes.
C．Rocks loosened by melting ice could be dangerous.
D．They wouldn't be able to walk on the melting ice.