In the 1800s, many people living in the cities in the united states died of infectious diseases such as cholera, which is caused by a bacterium that pollutes water. cholera is no longer a major problem in the united states. what is the most likely reason for the elimination of cholera as a major disease? a. advances in medicine have led to cures for cholera. b. people have learned the importance of washing their hands. c. sewage treatment plants have eliminated such pathogens from drinking water. d. regulations have prevented factories from dumping pollution into lakes and rivers.