What are the answers to the questions? (subject-verb agreement)

When i walked through arlington cemetery, i had a sense of reverence—a respect for the courage, dedication, and sacrifice of the souls buried here. using context clues, what is the meaning of reverence in the passage?

What is a mechanism by which organisms maintain homeostasis when the level of one substance influences the level of another substance or the activity of an organ.

Which description most clearly defines tone in literature