Area resident: Childhood lead poisoning has declined steadily since the 1970s, when leaded gasoline was phased out an...

Anita on June 21, 2018

@Ohemaa The main flaw in the argument, as noted in C, is that there’s an assumption that there aren’t any other (or no other significant) sources of lead.

B is suggesting circular reasoning - that is, assuming the answer to get to the answer. This isn’t what is happening here. You can check for circular reasoning by checking if the premises and conclusion are the same, which here we can tell they aren’t.