Which of the following describes a short poem consisting of five unrhymed lines?

The correct answer is a cinquain, which is a specific type of five-line poem that typically follows a specific syllable pattern or word count, while lacking a rhyme scheme. Cinquains are often characterized by their focus on imagery and concise expression, making them distinct from other poetry forms.

In contrast, a haiku is a three-line poem with a syllable structure of 5-7-5, focusing on nature and moments of beauty in a very compressed format. A limerick is a whimsical and often humorous five-line poem with a distinct rhythm and a specific rhyme scheme (AABBA). An ode, on the other hand, is a formal, often lengthy poem that expresses praise or admiration for a subject, typically characterized by its elaborate structure and elevated language.

Thus, the characteristics of a cinquain clearly define it as the correct choice for describing a short poem consisting of five unrhymed lines.