What is the "Simplified Sharpe Ratio" used in the performance evaluation of an investment strategy? Choose the response which best answers this question Select one: O a. This is the ratio of the average excess return and volatility of historical returns. We often use the annualised version of these statistics. We could omit the risk-free rate since, in recent years, it is virtually zero O b. This is the ratio of the average return and volatility of historical returns. We often use the annualised version of these statistics. Ideally, we would use the average excess return, however in recent years, the risk free rate is virtually zero O c. This is the ratio of the mean and volatility of returns when we assume a risk-free rate equal to zero O d. The "simplified Sharpe Ratio" is, in other words, what most investors call the "Sortino Ratio