Please show working out/theory

There are three risky assets described by the table below: Asset Expected returnReturn standard deviation 9.00% 12.00% 15.00% 3.00% 5.00% 8.00% 2 3 There are three investors X, Y and Z whose preferences represented by the utility function U = E(r)-0.52, where a is the risk-aversion coefficient, and is lowest for X and highest for Z. The risk-free rate is 3%. If they have to form a complete portfolio of the risk-free asset and one of the three risky assets, which risky portfolio(s) will be picked by investors X, Y and Z respectively? Select one: A. Asset 3 for investor X, Asset 3 for investor Y, and Asset 3 for investor Z B. Asset 1 for investor X, Asset 1 for investor Y, and Asset 1 for investor Z C. Asset 2 for investor X, Asset 2 for investor Y, and Asset 2 for investor Z D. Asset 1 for investor X, Asset 2 for investor Y, and Asset 3 for investor Z E. Asset 3 for investor X, Asset 2 for investor Y, and Asset 1 for investor Z