Answer:
B. her varied carols I hear.
Step-by-step explanation:
Galway Kinnell wrote his poem "Vapor Trail Reflected in the Frog Pond" condemns the involvement of the American government in the Vietnam War. Adopting the chanting style of another American poet Walt Whitman, Kinnell used the same style in his condemnation of the violence inflicted by the American troops.
The second part of the poem "Vapor Trail Reflected in the Frog Pond" has the lines "And I hear, coming over the hills, America singing, her varied carols I hear". This line is the same as that of Whitman's poem "I Hear America Singing" which begins with the similar lines "I hear America singing, the varied carols I hear."
Thus, the direct reference to Whitman's poem in Kinnell's poem is "her varied carols I hear."