Why is there a limit to the number of levels that a food chain can reach?

All but one describes an effect of aging on the digestive system. a) decreased acid secretion b) decreased elasticity of stomach c) capacity to resist damage decreases d) food remains in stomach for less time

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?

Which benefit of the community experience when its members have a hide level of health literacy