Make a correct sequence of age-sex Pyramids in ascending order in relation to the development:-
A. Declining Populations
B. Ageing Populations
C. Expanding Populations
D. Constant Populations
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → C, D, A, B
(C) Expanding Populations — first, the least developed. The pyramid is triangular with a wide base. High birth rates give many people in the lower age groups, as in Nigeria, a less developed country.
(D) Constant Populations — second. The pyramid is bell shaped and tapers towards the top, as in Australia. Birth and death rates are almost equal, so the population stays nearly constant.
(A) Declining Populations — third. The pyramid has a narrow base and a tapered top, as in Japan. Birth and death rates are both low, and growth in developed countries is usually zero or negative.
(B) Ageing Populations — last, the most developed. When birth rates stay low and people live longer, the share of old people grows. This happens in most developed countries.
Note 1: The given answer is as per the official NTA Answer Key. The NCERT book shows three types of age-sex pyramids: expanding populations (Nigeria), constant populations (Australia) and declining populations (Japan). ‘Ageing populations’ is not a type of pyramid in the book. A population ages when birth rates stay low for a long time, so an ageing population comes after the declining stage, at the most developed end. With this, the order C, D, A, B can be worked out from the book.
Note 2: This question is taken from the pre-rationalised NCERT book. The latest edition (2026-27) does not have this part. An extract of the pre-rationalised NCERT book is given below for the benefit of students.
Pre-rationalised NCERT: “Expanding Populations … The age-sex pyramid of Nigeria as you can see is a triangular shaped pyramid with a wide base and is typical of less developed countries. These have larger populations in lower age groups due to high birth rates.” “Constant Population … Australia’s age-sex pyramid is bell shaped and tapered towards the top. This shows birth and death rates are almost equal leading to a near constant population.” “Declining Populations … The Japan pyramid has a narrow base and a tapered top showing low birth and death rates. The population growth in developed countries is usually zero or negative.” “Ageing Population … Population ageing is the process by which the share of the older population becomes proportionally larger. This is a new phenomenon of the twentieth century. In most of the developed countries of the world, population in higher age groups has increased due to increased life expectancy. With a reduction in birth rates, the proportion of children in the population has declined.”
Fig. 3.1: Expanding Population; Fig. 3.2: Constant Population; Fig. 3.3: Declining Population |
