You Randomly Select 120 Healthy Individuals and Randomize Them into a Group

You randomly select 120 healthy individuals and randomize them into a group given a daily multivitamin and a group who does not take a daily multivitamin. You follow the sample for ten years and identify all cases of pernicious anemia which develop. Which statement is true?

A) You should NOT determine a relative risk since this is a cross sectional design
B) You can determine the RR for developing pernicious anemia from this data
C) Your exposure of interest is retrospective
D) You can only determine the odds ratio for pernicious anemia