Question

What is the poetic form of this excerpt from Robert Frost's "Mending Wall"?

Bringing a stone grasped firmly by the top
In each hand, like an old-stone savage armed.
He moves in darkness as it seems to me,
Not of woods only and the shade of trees.
He will not go behind his father's saying,
And he likes having thought of it so well

free verse
blank verse
ballad
sonnet
elegy