Consider a T-bill with a rate of return of 5% and the following risky securities:

Security A: E(r) = 0.10; Variance 0.04

Security B: E() = 0.09; Variance = 0.0225

Security C: E() = 0.12; Variance = 0.01

Security D: E() = 0.15; Variance 0.062

From which set of portfolios, formed with the T-bill and any one of the four risky securities, would a risk-averse investor always choose?