Answer:
The evidence that supports the author's reason.
Step-by-step explanation:
Just giving your view on atopic does not mean people will agree to your claim, some may doubt it, some won't even a cent the claim and some won't even bother to know anything about the claim.
Giving the major reasons does not mean it will be able to convince others. Just giving your reasons is like giving or stating your opinions. Giving your opinion is for others to think about it and build more reasons or opinions on it.
Giving an argument on the topic is just like rejecting people's opinion or lookiNg down on their opinions and that's not a good enough strategy to convince someone.
The topic just enables people to know what you are talking or arguing about. It's just to give people a reason to argue or listen to your claim.
The evidence that supports your reasons works.
After giving your reasons, you have to present an evidence or a group of evidences to make people believe or accept your claim.
For example, a police would ask for evidence in order to believe or accept your accusation or suggestion of a criminal because he can't just believe what he hasn't seen.
You have to let people know why your reasons are stated. They have to have a sense of understanding and object of assurance that your claim is true.
So the evidence that supports the author's reasons make a claim effective.