Final answer:
The most effective metaphor in poetry is an original comparison that offers new insights, avoiding clichés and sparking the reader's imagination.
Step-by-step explanation:
The kind of metaphor that works best in a poem is B. an original comparison that suggests something new. Unlike clichés, which have become overused and lack freshness, original metaphors create surprising connections and reveal new insights into the subject matter. These comparisons are valuable because they ignite the imagination and provide readers with a unique perspective. While very similar things (D) can serve for comparison, truly engaging metaphors often combine disparate elements to spark deeper thought.
It's important to note that while also make comparisons, often using the words "like" or "as," a metaphor asserts that one thing is another, thereby intertwining their meanings more closely. Vivid metaphors become the hallmark of memorable poetry, as they are able to communicate complex emotions and ideas succinctly and powerfully.