Which most likely is a causal relationship? A. An experimenter showed different causes for two patients' lung cancer. B. One experiment showed that all cancers can be cured by a new drug. C. Experimenters show a link between adult-onset diabetes and obesity. D. Experimenters show statistical data on diabetes drugs.

Answer: C. Experimenters show a link between adult-onset diabetes and obesity

On the statement above, there is clearly a causal relationship between the adult-onset diabetes and obesity according to researches and experiments. Causal relationship shows that there is one event is the cause while the other is the result.