You made good choices by selecting 3 (meter) and 4 (style of refrains).
Meter refers to the rhythmic structure of the lines in the poem, indicating how syllables are arranged and stressed, which is crucial for understanding its flow and musicality.
Style of refrains involves the repetition of lines or phrases throughout the poem, which can create emphasis, rhythm, and unity in the piece.
Overall, both elements significantly contribute to a poem's structure and its overall impact on the reader.