Suppose that many stocks are traded in the market and that it is possible to borrow at the risk-free rate, rf. The characteristics of two of the stocks are as follows:

Stock A: Expected return = 4% and standard deviation = 12.50%

Stock B: Expected return = 6% and standard deviation = 14.50%

If correlation between stock A and stock B is -1 (perfectly negatively correlated), then which of the following represents a value closest to equilibrium risk-free rate?