Which of the following statements is true?

a. Except for tax-exempt investors and tax-deferred accounts, annual tax payments increase investment returns.

b. The only way to maintain purchasing power over time is to invest in bonds.

c. After adjusting for taxes, long-term bonds consistently outperform stocks.

d. An asset allocation decision for a taxable portfolio that does not include a substantial commitment to common stocks may make it difficult for the portfolio to maintain real value over time.

e. None of the above