Answer:
A. It makes the poem easy to memorize.
Step-by-step explanation:
In the original question, you were asked about alliterative verse, not alternative verse.
While many forms of poetry use rhyme, the alliterative verse is a type of verse where alliteration is used to unify lines of poetry. Alliteration is a literary device in which nearby words begin with the same consonant (e.g. Black bug bit a big black bear - consonant B is repeated). Its main purpose is to create rhythm.
The rhythm was very important in epics. The epic is an old form of poetry, and originally, it was just an oral form. Oral poetry was created and transmitted without the aid of writing. Most people were illiterate and couldn't write or read. So, in order to make them easy to memorize, their creators used different tools, including rhythm. This is why the alliterative verse was important.