I think it would be “who weren’t able to go on the field trip”
Answer:
The speaker stops to see the snowfall in the woods but knows his responsibilities won't allow him to stay long.
Explanation:
The poem "Stopping By Woods On A Snowy Evening" by Robert Frost is a poem where the speaker is in a dilemma between his duty and what he wants to do. Stuck between admiring the snowy woods and his duty living in society places him in a contrasting position.
While the central idea of the poem is that the speaker wants to admire the beauty of nature, he also acknowledges that it is <em>"queer"</em> even for his horse to stop in the middle of the woods. But as a man living in a society, he <em>"ha[s] promises to keep, and miles before [I] sleep"</em>.
And through the presentation of how the speaker stops and admires the snowfall in the woods, he also knows that his responsibilities won't allow him to have this enjoyment/ leisure for a longer duration.
Thus, the correct answer is the third option.
