you invest $$1,000$ in a risky asset with an expected rate of return of $0\mathrm{.}15$ and a standard deviation of $\mathrm{.}20$ and a t bill woth a rate of return of $0\mathrm{.}05.$ if you want to form a portfolio with a standard deviation of $0\mathrm{.}08,$ what percentage of your money must be invested in the risk free asset and the risk asset

a$.30\%$ and $70\%$

b$.50\%$ and $50\%$

c$.60\%$ and $40\%$

d$.90\%$ and $10\%$

e$.$ cannot be determined