Final answer:
The citizens were not provided water that had been properly treated by eliminating chemicals to create potable, aesthetically pleasing drinking water.
Step-by-step explanation:
The aspect of the drinking water infrastructure that most failed the people of Flint was option A) The citizens were not provided water that had been properly treated by eliminating chemicals to create potable, aesthetically pleasing drinking water.
The switch from the Detroit municipal water supply to the corrosive Flint River water resulted in the contaminated water not being properly treated, leading to higher levels of lead in the water. This posed a serious health risk to the residents, particularly children, who were exposed to the poisoned water for an extended period of time.