Asset A has an expected return of $15\%$ and a reward$-$to$-$variability ratio of $0\mathrm{.}4.$ Asset B has an expected return of $20\%$ and a reward$-$to$-$variability ratio of $0\mathrm{.}3.$ A risk$-$averse investor would prefer a portfolio using the risk$-$free asset and

a$)$ asset $A$

b$)$ asset B

An investor's degree of risk avers

c$)$ no risky asset

d$)$ Answer undeterminable