Which of the following is true? a. No real population in nature ever fully meets the conditions of the HardyWeinberg equilibrium. b. The HardyWeinberg equilibrium shows that allele frequencies will remain constant except when some mechanism causes them to change. c. The HardyWeinberg model is a null hypothesis that describes what would happen in the absence of evolutionary change. d. Deviations from HardyWeinberg equilibrium can help researchers identify mechanisms of evolutionary change. e. All of the above