In which of the following research designs would it be MOST difficult to draw causal conclusions?

Question

Quizplus · Accepted Answer

Cross-sectional survey designs only measure variables at one point in time and do not allow for the manipulation of variables, making it difficult to determine causality. Longitudinal surveys at least measure variables at multiple points in time, but still may not allow for the manipulation of variables or control of extraneous variables. Laboratory experiments, on the other hand, allow for the manipulation of variables and control of extraneous variables in a controlled setting, making it easier to draw causal conclusions. Field experiments also allow for manipulation and control, but may be more prone to external validity concerns.

In Which of the Following Research Designs Would It Be