Question

at the beginning of which country the world population was one billion
twentieth century
twenty first century
nineteenth century
seventeenth century ​

Answer 1

Answer:

don't says about population

Explanation:

Answer 2

Answer:

nineteenth century

Explanation:

because 20th century The world's population was 6 billion and the world's population was 1 billion in 1804 but 1804 is not in option so 19th century is the correct answer