☁️My Answer☁️:
I believe the correct answer that best replaces the phrase "It's dark eyes dim and not at their prime" is A.) Its eyes were black diamonds but flat as a dime.
✧My Explanation✧:
I believe the correct answer is A, because a metaphor is a sentence or phrase that compares two things and it is a figure of speech that makes a comparison between two unlike things. As a literary device, metaphor creates implicit comparisons without the express use of “like” or “as.” Metaphor is a means of asserting that two things are identical in comparison rather than just similar. So, I took this knowledge that I have known about metaphors and picked the best answer option by first eliminating the answer options, C and D then eliminating answer option B.