Which of the following would decrease a portfolio s systematic risk?

a.Common stock with positive betais sold and replaced with Treasury bills.

b. Stocks with a beta equal to the market portfolio beta are added to a portfolio of Treasury bills.

c. Low-beta stocks are sold and replaced with high-beta stocks.

d. A stock is sold in favor of a different stock with the same beta.

e. The portfolio beta is less than one and the risk-free rate declines.