Look at the list of some types of data that can be use to describe a populated area.

1. Plants and animals in the area
2. Human population density in the area
3. Types of roads in the area
4. Water table levels in the area

Which types of data must be included in a model comparing risks of groundwater pollution of drinking wells in two different watershed areas?

A) 2 & 4 only
B) 1 & 2 only
C) 2 & 3 only
D) 1 & 3 only