I believe that the answer is his body will become a part of the earth, because 'bequeath' means to pass something on or leave to someone else, and he is leaving his body and letting it become one with the earth.
Answer:
B). That his body will become part of the earth.
Explanation:
'Song of Myself' is illustrated as one of the most acknowledged poems from his collection "Leaves of Grass". The poem celebrates 'individuality' (acknowledgment of self) and reflects the idea of 'transient' nature of human life. The poet describes the idea of the intermingling of the individual self with the 'universal self' and hopes for a mystical union with the almighty.
As per the question, in the given lines the poet suggests that 'his body will become a part of the earth' reflective of brevity of life(as reflected by 'I bequeath myself to the dirt') and thus, he anticipates a spiritual union of his self with the supreme authority(God). Therefore, option B is the correct answer.
