Final answer:
If a poem consists of ten lines, it can be written in blank verse which typically follows iambic pentameter, or it could be written in free verse which does not adhere to a specific meter or rhyme scheme. Since sonnets consist of fourteen lines, the poem would not be a traditional sonnet if it only has ten lines.
Step-by-step explanation:
The poem's structure can be determined by analyzing its use of meter and line count. Blank verse is traditionally written in iambic pentameter and typically does not rhyme. Since iambic pentameter consists of ten syllables per line, a poem written in this form could be composed of ten-line stanzas. On the other hand, free verse does not have a particular syllable count or meter. It allows for varying line lengths and rhythms, depending on the poet's intention.
A sonnet is a specific poetic form that consists of fourteen lines, usually in iambic pentameter but can deviate in modern poetry. It often features a volta, or turn in thought, but does not fit into the choices given if we consider the line count. Therefore, if the poem in question has ten lines, it could not be a traditional sonnet. Referencing the provided descriptions, if the poem has ten lines, it could either be written in free verse or blank verse. If it has twelve lines, it would not fit the description of either a sonnet or a traditional blank verse. Thus, the poem's structure can likely be identified as either 'syllabic meter, ten lines' or 'free verse, ten lines' if it indeed has ten lines.
Haiku, cinquain, and other named forms like tercet or quatrain refer to specific stanza or line structures and do not directly pertain to the overall poem length or meter as referenced in this question.