Free verse is a style of poetry that is defined as
a. being accessible to the common man.
b. having no single meter or verse structure.
c. including alternating rhyming couplets.
d. having no stanzas, only verses.

Free verse is a style of poetry that is defined as having no single meter or verse structure. By the term ‘free’ it means that the writer could do anything he wants to do with his verses. He does not need to follow any rules in writing poetry and even parallelism. He could do rhyming and combine it with no rhyming words and it is up to his discretion if the words he will be using will be based on dictionary or based on hid understanding alone.  

Icould be wrong but i would say b.