What type of population pyramid would a nation most likely have if it had a high birth rate 30 years ago and has a low birth rate now? 

constrictive
improving
stationary
expansive

1 answer

The most likely type of population pyramid would be "expansive." Expansive population pyramids are characterized by a wide base, indicating a high birth rate in a population. If a nation had a high birth rate 30 years ago and has had a decreasing birth rate since then, the population pyramid would show a large number of individuals in the younger age groups, gradually tapering off as the age groups increase. This would create a pyramid shape with a wider base and narrower top.