Final answer:
The best evidence that a poem is written in free verse is that it has no set meter which allows the poet to freely express without the constraints of traditional metrical patterns.
Step-by-step explanation:
The best evidence that a poem is written in free verse is that it has no set meter, which is option B. With free verse, poets are not bound by regular rhythms or rhyme schemes, giving them more freedom to express their thoughts and emotions in a way that might resemble ordinary speech. This flexibility allows the poet to impose a different kind of organization through thematic development, repeating imagery, and syntactic patterns, rather than adhering to a fixed metrical pattern.
As noted by poets like Robert Frost and Billy Collins, free verse's openness and reliance on elements such as tone of voice differentiate it from traditional forms of verse that rely heavily on consistent meter and end rhyme. Therefore, a poem's lack of regular meter is a defining characteristic of free verse.