Why is it relatively unusual to see old people in sub-sahara africa, especially in rural areas?

Most countries in Sub-Saharan Africa are in stage 2 of the Demographic Transition, which means that the population is increasing incredibly rapidly, even though the average death age in most countries is still relatively low. This increase in birthrate is due to increased economic activity.

b.

developed countries have tended to improve the environment, while developing countries have tended to damage it.