Answer:
A) the contrast between fire and the darkness.
Step-by-step explanation:
The most evident way in which the author achieves a sense of tension is by the opposition of the fire and the darkness. We know that the men are getting ready for something, however, we do not know what. Because of our lack of understanding, the darkness is all the more negative. Moreover, the fire is not only warm, but it is also defined as "cheery." The contrast between the two increases the tension in the story.