Final answer:
A longitudinal study or an experimental study would be the most effective research method to prove that smoking can lead to lung cancer, as shown by historical studies such as those by Doll and Hill.
Step-by-step explanation:
To test the theory that smoking cigarettes can lead to lung cancer, the type of research that would work best is a longitudinal study or an experimental study. The classic research by Doll and Hill used a case-control approach to establish a strong association between past smoking behavior and current lung cancer status.
Their subsequent longitudinal study, which observed almost 50,000 British male physicians over 50 years, provided even stronger evidence of the correlation between smoking and lung cancer. Such studies are key in demonstrating causation rather than just correlation, by following the same individuals over time and recording the incidence of cancer among them about their smoking habits.
Choices like case studies, interviews, or surveys might provide insights into individual experiences but are less powerful in establishing a causal relationship. The experimental approach would potentially be the most rigorous but raises ethical issues, as deliberately exposing subjects to a known carcinogen like tobacco smoke would not be permissible.