Answer: FINRA Series 7 certificate
Explanation:
The best certificate for her to get is the Series 7 certificate that is issued by the Financial Industry Regulatory Authority (FINRA). This certificate allows the holder to trade in every type of security there is except commodities and futures.
This includes fixed-income investments which are what Enny would like to trade in. Enny will have to write an exam to prove that she has the basic knowledge required to trade.