The greatest growth of human popultions today is occuring in

Developing nations

Explanation:

People in developing nations tend to have higher likelihood of being involved in sexual relationship without proper protection.

Many of individuals in developing nations also have very little awareness on the correlation between having more children with larger economic difficulties.

Both of these factors contributed to the increase of population.

if you ment which country has the largest population then its, China the country has the world's largest population (1.42 billion), followed by India (1.35 billion). The next five most populous nations - the United States, Indonesia, Brazil, Pakistan and Nigeria - together have fewer people than India.