Study the age pyramids ‘A’, ‘B’ and ‘C’ of the human given below and answer the questions that follow :

(a) Identify pyramids ‘B’ and ‘C’.

(b) Write the basis on which the above pyramids are plotted.

Correct Answer:
(a) B - Stable population, C - Declining population
(b) Age Distribution of male and female of human population

Explanation:
An age pyramid is a graphical representation displaying the proportion of various age groups in a population at any given time. As seen on the left side of the provided image, the population is divided into three ecological age groups:
1. Pre-reproductive group (represented by the bottom orange/yellow blocks)
2. Reproductive group (represented by the middle blue blocks)
3. Post-reproductive group (represented by the top purple blocks)

Part (a): Identifying Pyramids ‘B’ and ‘C’
- Pyramid B: Looking at pyramid B, the pre-reproductive age group (orange block) and the reproductive age group (blue block) are nearly equal in size. This indicates a stable birth rate and death rate, resulting in a zero or near-zero population growth rate. This shape is characteristic of a stable population.
- Pyramid C: In pyramid C, the pre-reproductive base (orange block) is noticeably narrower than the reproductive middle (blue block). This indicates a decreasing birth rate with fewer children being born, leading to a shrinking future reproductive group. This shape represents a declining population.

Part (b): Basis of Plotting
The above age pyramids are plotted based on the age distribution of males and females in a human population. Typically, for a given population, the percentage of males (often plotted on the left) and females (plotted on the right) in different age groups are depicted together to analyze the population's demographic structure and predict its future growth trend.