Final answer:
The best paraphrase of the final stanza 'I surmised the horses' heads toward eternity' in Emily Dickinson's poem is option d) I imagined the horses' heads pointing to the unknown.
Step-by-step explanation:
The best paraphrase of the final stanza 'I surmised the horses' heads toward eternity' in Emily Dickinson's poem is option d) I imagined the horses' heads pointing to the unknown. This line suggests that the speaker is picturing the horses' heads facing a mysterious and uncertain future.