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

		a. Common stock with positive beta is 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.