Citizen: The primary factor determining a dog’s disposition is not its breed, but its home environment.
Conclusion (As a result)
Breed-specific legislation could never effectively protect the public from vicious dogs.
Intermediate Conclusion
A dog's disposition is determined mainly by its home environment, not its breed.
Evidence
A bad owner can undo generations of careful breeding.
Legislation aimed at specific breeds would not address the effects of how humans raise and train dogs.
Evaluate
When we read Main Conclusion / Role, we are listening actively for upside-down arguments (80% of the time the main conclusion comes earlier than its evidence).
So we may have correctly suspected that the First Sentence was a conclusion. It was indeed supported by the second sentence.
But we can also see from "As a result", that the third sentence supports the fourth.
(The fifth sentence is a weird bonus idea tacked on by Moreover, but not supported by anything in particular).
Since 3rd supports 4th, we know that 4th is also a conclusion.
So when it comes to our two conclusions (the 1st and 4th sentences), which one is supporting the other?
It makes more sense to say
than to say, .
Goal
So we know that the 4th sentence is our main conclusion, supported by the first three sentences.
Look for a restatement of "breed-specific legislation could never effectively protect the public."