Final answer:
The words that establish the tone in Byron's 'She Walks in Beauty' are 'grace,' 'serene,' and 'divine,' which convey a tranquil and profound admiration.
Step-by-step explanation:
The words that help determine the tone of the poem "She Walks in Beauty" by George Gordon Byron are most accurately reflected by choice (a). The descriptive words such as grace, serene, and divine capture the subtle elegance and profound admiration the speaker holds towards the subject of the poem. These choices contrast with options (b), (c), and (d) as they are imbued with a tranquil beauty and celestial purity, rather than the themes of mystery and sorrow, ecstatic joy, or enchanting twilight suggested by the other options. Byron's choice in words like 'grace' and 'divine' specifically paints a picture of peacefulness and a spiritual, ethereal beauty, which is central to the poem's contemplative and admiring tone.