Final answer:
A retrospective chart review is classified as (b) Level IV evidence in the hierarchy of medical evidence since it is a non-controlled study that relies on historical data.
Step-by-step explanation:
A retrospective chart review is a type of research design where past records are used to collect data and examine outcomes. In the hierarchy of evidence, a retrospective chart review is typically considered as a Level IV evidence. This is because it consists of case series without controls, which are lower on the evidence hierarchy than randomized controlled trials, cohort studies, or case-control studies.
As per the question's scenario, the student is examining patient falls and the use of a fall rating scale through retrospective chart review. Since the design does not involve higher levels of evidence such as prospective studies or randomized trials, the appropriate answer is (b) Level IV.