The most common source of infectious diseases in water supplies is . a. algal blooms b. sewage c. surface runoff d. none of the above Please select the best answer from the choices provided A B C D

The correct option is B

b) sewage

Explanation:

Sewage reffers to domestic or municipal wastewater,it is a type of wastewater which is released to the environment by a community of people.It could be industrial effluents, or stormwater from streets. It can be identified by the amount of chemical and toxic constituents, the status of bacteria present.

There is release of sewage into streams and rivers around the world today even in an untreated form, as a result of these the respiration as well as the available Oxygen is consumed because of the organic carbon present in the untreated sewage which makes the river toxic and get people infected with diseases if consumed.

Sewage is made up of different harmful microbes, human can contact diseases from these microorganisms when bathing with the water or make use of it to cook.

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current