This poem by William Blake has the purpose of reporting the life suffered by the chimney sweepers. Besides the chimney sweepers being children (often orphans), this was a very dangerous and poorly paid job. Blake wanted to express through this poem that the children who did this service were mistreated and treated almost as slaves, lived in poverty and misery, were malnourished and sick.
I know that you may have already have already answered the question. However.for those that are wonder the answer is D. stanzas. The poem is structured in a group of lines.