Which of the following is correct about impairment of goodwill for a subsidiary? Select one: a. If the fair value of the subsidiary is less than the investment balance, the investment is deemed impaired. b. The future expected cash flows of the investment are compared with the book value of the investment. c. If the book value of the subsidiary is less than the investment balance, the investment is deemed impaired. d. The fair value of the subsidiary is compared with the fair value of the investor's equity investment account