Niko is analyzing a cereal advertisement that suggests a rival cereal brand uses artificial ingredients and an excess amount of sugar. what persuasive technique is being used?

The persuasive technique that is being used here is name-calling.
This means that this cereal company is using, usually fake news and no evidence to say bad things about the rival company, disregarding whether it is actually true or not. People will see this cereal ad and believe it, regardless of whether there are any evidence to prove the claims.

Dude i have no idea what that is?