The process by which a country's population becomes smaller because its birth rate and net migration are too low to replace those who die and emigrate is called

Population Shrinkage (or Population Decline)

Explanation:

It can be used to refer to long-term demographic trends, such as urban decay or rural exodus, but is also commonly used to describe large population reductions due to violence, disease or other disasters. A good example is Japan, where the young population is small in contrast to a huge elderly population. In this case, the Population Shrinkage is caused by the less of birth, and the populational control executed by the Japanese government.

the declaration states, “we hold these truths to be self-evident, that all men are created equal, that they are endowed by their creator with certain unalienable rights, that among these are life, liberty, and the pursuit of happiness….”

answer; opportunities to further the healthy development to deal with the crisis of the next stage;