I believe the answer is B
The main idea of a poem is for the author to get a point across to the reader. The poem is supposed to give emotion or a feeling towards the reader. The author wants the reader to understand what point he or she is trying to make. People can learn important lessons or phrases from poems. It gives the reader a more deeper understanding of what they are reading. In summary, the main idea is what the author is trying to teach or personify towards you.
Jim is glad to see Huck an embraces him because he is glad to know that he is ok.