1. which section of the population comprise the main workforce
2. how is human resorce important for a country
3. why has there been a general decline in the deadth rates thoughout the world?how has this affected the world population

Due to paucity of time, It is feasible to answer one of your question:

2) how is human resource important for a country?

Ans: People are nation's greatest resource of importance for a country. Nature's bounty is useful only if people find them necessary and useful. People have demands that forces them to take up activities and their abilities turns them into resources. They act on other resources and utilise them to develop the infrastructure of a country.