The first rays of sun illuminated the frost on the inside of the window. Jack knew then that the temperature had dipped below zero overnight. The tiny cabin on Mount Rainier was little more than a shack. It had smelled musty when he and Armando first entered it last night, but the strong odor of smoke from the fire filled his nostrils now. Jack was glad to see that Armando was sleeping on the tattered cot. His friend had fallen more than 30 feet onto a rocky ledge. Jack was certain that Armando’s leg was shattered.
Jack began to think of the treacherous route back to the nearest town. He would have to cross rugged terrain and frozen streams. But Jack knew that he would have to make it there today to find a doctor. Jack drew in a deep breath and began to pack. As his resolve grew, his shaking hands began to steady. He would not let his friend down.

Which details of the setting are most important in conveying the mood?

A. rays of sun, tattered cot

B. below zero, rugged terrain, frozen streams

C. musty, the inside of the window, smoke from the fire

D. last night, nearest town