It has to be "B", a horror movie, the whole novel is a shocking, as we simply do not know what causes the metamorphosis and how difficult for everybody it was to take care of Gregor (the main character who undergoes the metamorphosis).
A cartoon would be more fit for an adaptation or satire, the same idea for a musical, for the documentary it would only work if the documentary was about Kafka, his work or the book itself.
