Which of the Following Statements About Natural Experiments Is FALSE

Which of the following statements about natural experiments is FALSE?

A) Natural experiments can be used to study phenomena that cannot be ethically studied using true experiments.
B) Natural experiments are essentially correlational studies, so we cannot draw causal conclusions from their findings.
C) Of the various types of field studies, natural experiments allow the researcher the most control over the independent variable.
D) It is never possible for participants to be randomly assigned to conditions of an independent variable in a natural experiment.