In a National Health Study, Begun in 2012, Thousands of Nurses

In a national health study, begun in 2012, thousands of nurses have been participating in ongoing research to better understand the effects of omega-3 fish oil and vitamin D-3 upon cardiovascular health and bone health. Subjects are randomly assigned to experimental or control group, for the two variables. Data about cardiovascular health and bone health will continue to be collected over many years. This study could be an example of what types of research?

A) Prospective
B) Retrospective
C) Factorial study
D) Crossover design
E) Descriptive
F) Correlational
G) Experimental
H) Quasi-experimental