Which of the following statements is CORRECT regarding studies of character displacement? Select one: O a. Fenchel's (1975) early conclusions regarding character displacement in mudsnails have been confirmed by subsequent studies. O b. Grant (1975) proposed a null hypothesis for character displacement with his clinal variation model o c. Brown and Wilson (1956) provided clear, unambiguous data for character displacement with their rock nuthatch data. O d. None of the above