Final answer:
Zitkala-Sa thinks the telegraph poles are moaning when she puts her ear to them because of her active imagination.
Step-by-step explanation:
Zitkala-Sa thinks the telegraph poles are moaning when she puts her ear to them because she is imagining the sound due to her active imagination. This can be seen in the passage where she says, 'I pressed my ear against the poles and listened with all my ears.' Since she is a young child and has a vivid imagination, she is attributing the moaning sound to the telegraph poles, even though they do not actually make any sound.