Question

Which term best describes the expression 137 rabbits per km 2

Answer 1

There are two terms: Population = 137 Rabbits
& Area = per km2

We can calculate/define Population Density" from this data by:
Population density = number of individuals / per unit area (in Km²)

In short, Your Answer would be "Population Density"

Hope this helps!

Answer 2

The term for this would be density because for every square of land that is 1 km by 1 km (km 2), there is 137 rabbits. Hope I helped!