Which country (or countries) has the "youngest" population, that is, the highest proportion of population under age 15?
Which country (or countries) has the "oldest" population, that is, the highest proportion of population over age 64?

Youngest: Niger

1. Niger — 50.12% under 15.

Oldest: Japan

Japan has the highest old-age dependency ratio of all OECD countries – there is one person over 65 for every two people between the ages of 20 and 64.

Explanation:

answercharacteristics of place include things like economic activity, architecture,and culture,all of which are human elements that alter or can be influenced by the environment;