Final answer:
The survivorship curve is the best at showing the life expectancy of an individual within a population, representing the number of individuals alive at each age interval, and identifying mortality patterns by various types for different species.
Step-by-step explanation:
The best option for showing the life expectancy of an individual within a population is c) Survivorship curve. A survivorship curve is a graphical representation that displays the number of individuals surviving at each age interval for a given species. This tool is widely used by population ecologists to understand the life histories and mortality patterns within a population.
There are three types of survivorship curves. A Type I survivorship curve is characterized by low mortality in early and middle years with an increase in mortality rates in older individuals. Humans and most mammals exhibit this type of curve. In Type II curves, mortality is relatively constant throughout the lifespan, meaning death is equally probable at any age. Birds are a common example of such a curve. Lastly, Type III survivorship curves show very high mortality rates at young ages but much lower mortality for individuals who survive to older age groups, a pattern often seen in trees.