12. Which of the following statements can be considered market manipulation? A brokerage promotes stocks of a firm as prospect of good return when the firm is actually under SEC investigation b. A mutual fund sells an unusually large amount of IBM stock to avoid future losses High frequency traders using high speed computers can take advantage of minute changes in stock buy-sell margins instantly before discrepancies fall back into the normal range d. The CEO of a failing firm affirms the firm's rosy forecast right before the facts come out c. None of the above