The correct statement about demographic trends around the world is:
The world’s population is getting older on average because of long life expectancy in some places.
This reflects the trend of increasing life expectancy in many regions, especially in developed countries, contributing to an aging population. Other statements provided are misleading or inaccurate. For example, while some regions may have high fertility rates, overall, many developed countries are experiencing low fertility rates and population stability or decline. Additionally, high fertility rates do not correlate with longer life expectancy in developed countries.