Question

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

Explanation:

To determine the most common source of infectious diseases in water supplies, we analyze each option:

• Option a: Algal blooms mainly cause issues like oxygen depletion or toxin production in water but are not the primary source of infectious diseases.
• Option b: Sewage contains various pathogens (bacteria, viruses, parasites) from human/animal waste. When sewage contaminates water supplies, it readily introduces infectious agents, making it a common source.
• Option c: Surface runoff can carry contaminants, but it's less likely to be the most common source of infectious diseases compared to sewage, as runoff's pathogen load is often lower and more variable.
• Option d: Since option b is correct, this is invalid.

Answer:

b. sewage