Final answer:
A researcher should use a designed experiment to claim causation between an explanatory variable and a response variable.
Step-by-step explanation:
When a researcher wants to claim causation between an explanatory variable and a response variable, they should use a designed experiment. A designed experiment allows the researcher to manipulate the explanatory variable and observe the resulting changes in the response variable. This helps establish a cause-and-effect relationship between the two variables by controlling for other factors that could influence the outcome.