Management Performance of A Single Portfolio or Security Discussion

I’m working on a management question and need the explanation and answer to help me learn.

ABC Company Discussion Question 

ABC Company has hired you to explain the criteria for assessing the performance of a security, specifically expected rate of return, standard deviation of rate of return, and coefficient of variation (CV). They also want you to show how, by forming a portfolio, an instrument can be generated that has properties better than each of its constituents in terms of the standard deviation of rate of return and CV. How would you explain and show this information to ABC Company?