Final answer:
An experimental study is the best option to support a causal claim as it allows for manipulation of variables and measurement of their effects.
Step-by-step explanation:
The best option to support a causal claim is a experimental study. In an experimental study, researchers manipulate the independent variable and measure the effects on the dependent variable. This allows for strong evidence of a cause-effect relationship between the variables.
For example, if researchers want to determine if a new medication causes a decrease in blood pressure, they can assign participants randomly to two groups: one that receives the medication and one that receives a placebo. By comparing the outcomes of the two groups, they can determine if the medication is the cause of the decrease in blood pressure.