I am not quite sure if I know where the computer lab is. I heard it is open for all students, though. Where would I find it?
Assuming your options are <em>infinitives, repetition, adjectives, and punctuation, </em>the correct answer is infinitives.
The answer is rather simple when you think about it - there are no infinitives in this passage, so obviously they cannot contribute to any mood. There are repetitions (the word fog is constantly being repeated), there are a lot of adjectives, and some punctuation marks - all of which contribute to the dreariness of this excerpt.
You is the use it please.