The figures below show plots of monthly excess returns for two stocks plotted against excess returns for a market index. Excess Returns Stock A Excess Returns Stock B RA- TA-rf RB-IT rB-rf RM-rf RM-rf Which stock is likely to further reduce risk for an investor currently holding her portfolio in a well-diversified portfolio of common stock? Stock A Stock B There is no difference between A or B. The answer cannot be determined from the information given