### Step-by-Step Solution:
1. Understand the Equation:
The equation given is `total number of people in an area divided by the area in [tex]$km^2$[/tex] (or [tex]$mi^2$[/tex])`. This equation calculates how many people live per unit area of land.
2. Define the Concepts:
- Growth Rate: The rate at which a population increases or decreases over a specific period of time, usually expressed as a percentage.
- Population Density: The number of individuals living per unit area of land. It is calculated by dividing the total population by the land area.
- Death Rate: The number of deaths in a population over a specific period, usually expressed as a rate per 1000 individuals per year.
- Carrying Capacity: The maximum number of individuals that an environment can support sustainably without degrading.
3. Analyze the Equation:
- The given formula calculates how many people are present in a given unit of land area.
- This directly aligns with the definition of population density, which measures how densely the population is distributed in a given area.
4. Eliminate Other Options:
- Growth Rate involves time and changes in population over time, which is not represented by the given division of people by area.
- Death Rate also involves time and the number of deaths, which has no relevance to the division of total people by land area.
- Carrying Capacity is about the environment's ability to support a population and is not calculated using the population divided by area.
5. Conclude the Best Answer:
The equation “total number of people in an area divided by the area in [tex]$km^2$[/tex] (or [tex]$mi^2$[/tex])” calculates the Population Density.
Therefore, the best answer from the choices provided is:
b. Population Density
