Answer:
a. a child
Step-by-step explanation:
"Song of myself" is a poem in the book "Leaves of Grass," first published in 1855 by the American journalist Walt Whitman. This book was a watershed in the Poetic Letters, because it definitively broke with the stylistic rules metric and rhyme until then adopted by the American poets, who clearly imitated the European poets.
In "Song of myself" the poet states that a child asked him what blade of grass was and he replied that he knows what it is as much as the child knows. This is present in the following stanza:
"One child said, What is the blade of grass? bringing a
tuft in his hands;
What do I tell her? .... I know as much as her what
is the blade of grass."