The correct answer to this open question is the following.
Suppose that in a given advanced nation, birth rates are quite low, with about two children per family. Life expectancy, however, is also fairly low for an advanced nation, averaging about 67, due to a high prevalence of alcoholism and tobacco consumption, as well as rampant environmental pollution. The shape of the population pyramid in this nation would resemble a diamond.
A population pyramid is a graphic that shows how age is distributed in different groups in a determined country. It has different shapes, according to the growth of the population in that nation. The population pyramid is usually shown in histogram bars, stacked one over the other, with the size of the population depicted on the axis of the "x" and the age groups in the axis of the "y."