Read the poem "Knowledge" by Louise Bogan. Then, answer the question that follows.

[1]Now that I know
How passion warms little
Of flesh in the mould,
And treasure is brittle,—

[5]I'll lie here and learn
How, over their ground,
Trees make a long shadow
And a light sound.

Which of the following descriptions best defines the structure of Bogan's poem?

Two couplets
Two quatrains
Two octaves
Two tercets