The correct answer is A. permanent.
The word “obsolete” means no longer in use or no longer fashionable. In the context of the question, the speaker is saying that comparisons in poetry are no longer used. This suggests that comparisons in poetry were once used, but are no longer. This means that the correct answer must be a word that means “not changing or not able to be changed.” Of the four options, only “permanent” means “not changing or not able to be changed.”
The word “ancient” means “very old.” This does not make sense in the context of the question, because the speaker is not saying that comparisons in poetry were once used, but are no longer used because they are too old.
The word “renovated” means “made new or improved.” This does not make sense in the context of the question, because the speaker is not saying that comparisons in poetry were once used, but are no longer used because they have been improved.
The word “recent” means “happening or coming recently.” This does not make sense in the context of the question, because the speaker is not saying that comparisons in poetry were once used, but are no longer used because they are too recent.