Which is most likely a casual relationship?

1.an experiment showed different causes for two patients lung cancer
2.one experiment showed that all cancers can be cured by a new drug.
3.experimenters show a link between adult-onset diabetes and obesity.
4.experimenters show statistical data on diabetes drugs.

The correct answer is: 3.Experimenters show a link between adult-onset diabetes and obesity.

Relationships between two observed variables can be causal or non-causal. When one of them has a direct influence on the other it is called a causal relationship. On the other hand variables can be related without direct influence one to another and those relationships are non-causal.