Explanation : As one moves from left to right along an efficient frontier, the increase in
return with every unit increase in risk keeps decreasing because the slope
of the efficient frontier continues to decrease.
Explanation : Since Investor A only invests in risky assets, the highest return for a given
level of risk is indicated by the efficient frontier. Investor B invests in the
risk free asset as well. For him, the highest return for a given level of risk
is indicated by the capital allocation line (CAL).