Sharon Braxton is one of your most treasured clients. She's an investment whiz and loves bond investments. She wants to buy a bond with the highest possible return in a normal interest rate environment, regardless of risk. Which of the following options is likely to be the best fit for her request? 5 year US Treasury bond, rated AAA 15 year secured note, rated BBB. 6 month secured note, rated B 15 year corporate bond, rated B 6 month corporate bond, rated AA