Answer:
1. Population aging is the process in which there is increase in the median age of the population. This might possible due to the the decrease in the fertility rate or younger children vulnerability. The disease or death rate is high among the elder population.
2. The population aging might occur due to the difference in the birth rate, death rate, immigration and emigration among the population.
3. The main reason for the population aging in the U.S. is due to the better medical facilities and advancement in the health techniques. The increase in the old age people and due to the better employments.
