Final answer:
Experimental studies are best for depicting true cause-and-effect relationships because they manipulate one variable and control for others, unlike correlational studies which can only show if there is a relationship. Hence, option (b) is correct.
Step-by-step explanation:
The type of studies that best depict true cause-and-effect relationships between variables are experimental studies. Correlational studies can reveal whether there is a relationship or correlation between two variables, such as the examples that more smoking is correlated with higher lung cancer risk or more exercise with lower lung cancer risk. However, they cannot prove causation. This is because they do not control for all variables that might affect the outcome.
Experimental research, on the other hand, involves the manipulation of an independent variable and the measurement of its effect on a dependent variable, controlling for other potential confounding factors. Therefore, they can more confidently suggest that changes in one variable directly cause changes in another. This is why, when it comes to establishing causality, experimental studies are the preferred method over correlational or observational studies.