A Population That Is Decreasing in Size Will Have an Age-Structure

A population that is decreasing in size will have an age-structure histogram shaped like a(n) :

A) pyramid, with a wide base at the bottom representing a large number of young individuals.
B) rectangle, with an (roughly) equal number of individuals in each age group.
C) inverted pyramid, with a narrow base representing a small number of young individuals.
D) diamond, with a wide center depicting a large number of individuals that have reached reproductive maturity.