What was the main conclusion of Chapter 11 on risk and modern portfolio theory?

	a.	That net present value is the best financial decision rule for a portfolio
	b.	That the stock market is efficient
	c.	That beta measures the risk of a stock held by itself
	d.	That portfolio risk is not the sum of the individual risks in the portfolio
	e.	That investors will be indifferent when choosing between two portfolios that have equal expected return