The fda requires retention of investigational drug study records for

The FDA requires retention of investigational drug study records for  The answer is C. At least two years after the investigational drug's approval by the FDA
An investigator shall retain records needed to be preserved under this part for a period of two years following the date a marketing operation is approved for the drug for the explanation for which it is being investigated

Processes above and be sure to mention the movement of electrons and energy as the carbon atom moves from one reaction to another.