What is one of the most common reasons for unintentional plagiarism?

“simile” by n. scott momaday what did we say to each other that now we are as the deer who walk in single file with heads high with ears forward with eyes watchful with hooves always placed on firm ground in whose limbs there is latent flight source: momaday, n. scott. “simile.” the language of literature. new york: mcdougal littell, 2006. 265. print. which of the following techniques does this poem use? i. simile ii. sensory imagery iii. allusion i and ii i and iii ii and iii i only