Population pyramid expanding shape – UGC NET Question

An expanding population pyramid has a broad base representing many children and a sharply narrowing top representing fewer elderly people. This pattern signals high fertility and a large youth cohort in the population. It is typical of societies in earlier stages of demographic transition where birth rates remain high and death rates have started to decline. Thus, a wide-based pyramid indicates a youthful, rapidly growing population, as described in option B.

Option A:
Option A is incorrect because low birth and low death rates with an ageing population produce a more rectangular or top-heavy pyramid, not one with a very wide base. Such structures are characteristic of advanced demographic transition, not expansion.

Option B:
Option B is correct since high birth rates ensure many births each year, producing a large base, and improvements in health allow many children to survive into adulthood. The narrow top reflects fewer older persons in relative terms.

Option C:
Option C is incorrect because zero population growth would show relatively similar proportions in successive age groups, giving a more column-shaped pyramid. A wide base contradicts the idea of stable numbers.

Option D:
Option D is incorrect because a declining population with very low fertility would have a narrow base and a relatively larger proportion of older adults. This is the opposite shape of an expanding youthful population.