The fetid mound of waste near the town was a major cause of the epidemic.

Answer: Option C

Doomed : likely to have an unfortunate and inescapable outcome; ill-fated.
Dangerous : able or likely to cause harm or injury.
Stinking : foul-smelling.
Stagnant : (of a body of water or the atmosphere of a confined space) having no current or flow and often having an unpleasant smell as a consequence.
Fetid : smelling extremely unpleasant.

Synonym of Fetid is Stinking