Fix grammaticality of the sentence: Aging population is a global issue nowadays, especially in the developed countries.
The population of the world is aging.
The world is aging.
The world is aging.
The world is aging.
The world is aging.
The world is aging.
The world is aging.
The world is aging.
The world is aging.
The world is aging.
The world is aging.
The world is aging.
The world is aging.
The world is aging.
The world is aging.
The world is aging.
The
The United States is a country that is aging.
The United States is a country that is aging.
The United States is a country that is aging.
The United States is aging.
The United States is aging.
The United States is aging.
The United States is aging.
The United States is aging.
The United States is aging.
The United States is aging.
The United States is aging.
The United States is aging.
The United States is