In how many years the world population grew from 5 billion to 6 billion ?

6 years 8 years 10 years 12 years

12 years

Earlier it took more than a million years for the human population to reach one billion mark but it took only 12 years for it to rise from 5 billion to 6 billion, this is due to high birth rates and low deaths rates due to growing technology and improved medical facilities.