Population density is defined as the average

Step 1: Analyze the question The question asks for the definition of population density. Break the term into two parts: "population" (the number of people) and "density" (how much of something exists in a given space).

Step 2: Explain the concept Population density measures how crowded an area is. The formula is:

Population density = Total population ÷ Total land area

It is usually expressed as persons per square kilometre (persons/km²).

Example: If a town has 50,000 people living on 25 km² of land, its density is 50,000 ÷ 25 = 2,000 persons per km².

Step 3: Evaluate each option

• A. Number of people in the capital town: Wrong. This only counts people in one town and doesn't relate them to area.
• B. Number of people living in a unit area: Correct. This matches the formula, with people divided by a unit of land such as 1 km².
• C. Number of human resources: Wrong. This is a vague idea about the labour force or manpower, with no mention of area.
• D. Number of deaths and births in a unit area: Wrong. Births and deaths relate to vital statistics (natural population change), not density.

Step 4: Answer Population density is the average number of people living in a unit area, so the answer is B.

Tip: Think "density = amount ÷ space". Whenever you see density in Geography, look for an option that relates a quantity to an area. Don't confuse it with distribution (how people are spread out) or population growth (births, deaths and migration).