Answer the following question given this paragraph: 

Figure 19.4 Survivorship curves show the distribution of individuals in a population according to age. Humans and most mammals have a Type I survivorship curve, because death primarily occurs in the older years. Birds have a Type II survivorship curve, as death at any age is equally probable. Trees have a Type III survivorship curve because very few survive the younger years, but after a certain age, individuals are much more likely to survive.


Q: Survivorship curves show the distribution of individuals in a population according to what metric?

 Choices:

- weight

- height

- birth rate

- age

A:
age
