Which of the following figures is a prominent symbol within W.B. Yeats's poetry?

The rose is a prominent symbol in W.B. Yeats's poetry, representing a range of themes including beauty, love, and the complexities of human experience. Yeats often employed the rose as a multifaceted symbol, particularly in works that explore the interplay between idealism and realism, as well as the tension between the spiritual and the physical realms.

One of the most notable instances is in the poem "The Song of Wandering Aengus," where the quest for the elusive and transcendent beauty of the rose conveys a sense of longing and the search for deeper meaning in life. Furthermore, the rose appears in Yeats's "The Rose" collection, serving as a central motif that captures his romantic ideals while also reflecting the bittersweet nature of love and desire.

In contrast, the other figures mentioned—such as the swan, phoenix, and butterfly—are present in his work but do not encapsulate his poetic themes as thoroughly or consistently as the rose. Each of these figures has its own unique symbolic implications, but they do not carry the same extensive weight across Yeats's body of work. Thus, the rose stands out as a quintessential symbol in Yeats's exploration of the human condition.