Bill Smith is evaluating the performance of four large-cap equity portfolios: Funds A,B,C, and D. As part of his analysis, Smith computed the Sharpe ratio and the Treynor measure for all four funds. Based on his finding, the ranks assigned to the four funds are as follows: The difference in rankings for Funds A and D is most likely due to: a difference in risk premiums. a difference in returns. different benchmarks used to evaluate each fund's performance. a lack of diversification in Fund A as compared to Fund D