Use the Following Information for Questions

Use the following information for questions:
Suppose you were to read about a study showing that people who sleep less than five hours a night have twice as much risk of a premature death as people who sleep seven or eight hours a night.
-Can you conclude that sleeping the shorter hours causes a higher risk of premature death?

A) No, because the result was clearly based on an observational study.
B) Yes, because the result was clearly based on a randomized experiment.
C) The answer depends on whether the research was based on an observational study or a randomized experiment, and it isn't obvious which was used.
D) No, because the baseline risk of premature death is not given.