Final answer:
Cohort studies have high external validity but limited control over variables, while RCTs with random assignment have strong internal validity but may have limited generalizability. The correct answer choice that reflects these characteristics is A.
Step-by-step explanation:
The strengths and limitations of cohort studies compared to Randomized Controlled Trials (RCTs) are as follows:
- Cohort studies often have high external validity because they are observational and can include a diverse population mirroring real-world settings. However, they have limited control over variables since they do not manipulate conditions but instead observe natural occurrences over time. This can lead to less strong conclusions about cause and effect due to potential confounding variables.
- RCTs, on the other hand, involve random assignment and the deliberate manipulation of an independent variable to assess its effect on a dependent variable. This leads to strong internal validity and the ability to infer causality. However, the controlled conditions and sometimes narrower participant selection may limit the generalizability of the results to the wider population.
The best answer choice matching these characteristics is A) Cohort studies: High external validity, Limited control over variables; RCTs: Random assignment, Limited generalizability.