Which of these species typically has a mortality rate that remains fairly constant over an individual's life span? which of these species typically has a mortality rate that remains fairly constant over an individual's life span? humans grasses robins elephants oysters?

The correct option is robin. Scientists usually draw survivorship curve to determine the pattern of mortality and survival in different species. The graph usually show three basic patterns, some species produce a lot of offspring but only a few survive to the stage of active reproduction, some produce a small number of offspring but a large number of them survive to adulthood while the rest of the species are intermediate and have a fairly constant rate of mortality and survival. Robin falls into this last group.