Electric utility companies have historically paid high dividends to their shareholders. Many retirees include the stocks of these electric utilities in their portfolios. On the other hand, biotechnology companies typically pay little or no dividends so they can reinvest for research and development. Many of the biotech company's stockholders are in their peak income-earning years. Which of the following dividend theories best explains these results? -Select- a. Dividend irrelevance theory b. Tax preference theory c. Clientele effect d. Catering theory