Which of the following statements best describes the conclusion drawn by Brown in the highlighted portion? A. A change in tide schedule is the primary influence on an oyster's rhythms. B. A change in tide schedule may be an important exogenous influence on an oyster's rhythms. C. Exogenous influences, such as a change in tide schedule, seldom affect an oyster's rhythms. D. Endogenous influences have no effect on an oyster's rhythms. E. Endogenous influences are the only influences on an oyster's rhythms.