Final answer:
The research question type focused on explaining a cause-and-effect relationship is Causal. Such questions are designed to establish a causal link between variables, which cannot be confirmed with observational studies as they don't control for other influential variables. Option number C is correct.
Step-by-step explanation:
The research question type that is focused on explaining a cause-and-effect relationship is C) Causal.
Explanation of Research Question Types
A Descriptive research question aims at describing the characteristics of a phenomenon or a group of subjects. Comparative research questions are designed to examine the differences between two or more groups. Causal research questions, on the other hand, seek to determine the cause of a particular effect, thus establishing a cause-and-effect relationship.
Finally, Exploratory research questions are used to explore a subject in-depth where little is known to formulate more precise research questions for future studies.
Observational studies cannot establish causation because they can demonstrate a correlation, but they do not control for variables that might influence the outcome, which is why a controlled experiment is essential to prove causality effectively.
For example, in an observational study, one might find a positive correlation between the number of hours spent studying and the grades obtained, but one cannot conclude that increased study hours cause better grades without ruling out other variables, such as prior knowledge or intrinsic student motivation.