Filth (like sewages)= how to keep it from potable water sources. Crime = too many poor people and not enough income available.
Disease = they were pretty dirty people, disease & death were at high rates.. many infected bodies to dispose of.
It’s (b) sorry for answering late
A muckraker is a journalist who devotes their work to uncovering topics that might be overlooked or ignored by the powers that be. That said, a muckraker is D a writer who exposes unsafe working conditions.