Answer:
I think A, He'd get experience working with rhyme.
Explanation:
From looking it up Clerihews is more poking fun, so I don't think anything deep would be the answers.
Maybe try zooming in a little more :)
This happens quite a lot in verbs e.g run to running. It is because you double the last consonant in a one-syllable noun for it to become a verb. (Keep in mind there are exceptions to this rule.)
