Two medical researchers, researcher a and researcher b, have developed drugs to combat asthma. both researchers believe their drug to be the most effective. what results would confirm that researcher a’s claim about the drug is valid?

Ok, in this case, but researchers think that their drug is better than the other one, so:

What would prove that researcher A is correct about it?

Ok, researcher A and researcher B need to test their drug to see the effectiveness of it (and to see if there are some problems with the drug)

Then, if the drug A has a bigger percentage of effectiveness or/and less secondary effects than drug B, we can conclude that drug A is the most effective and that researcher A's claim is correct.