Which factor has contributed most to an increase in earths population

Food production, health care services, immigration...

Explanation:

I'd say health care services or immigration is one of the answers. If we didn't have certain medicines, there wouldn't be as many people.

Factors that cause population growth include increased food production, improved health care services, immigration and high birth rate. These factors have led to overpopulation, which has more negative effects than positive impacts.

The world population today is over 7 billion and the number is increasing with each passing year. Increased food production has made food available to areas with drought and famine. Proper health care facilities and services have helped to cure and control different diseases. There are more births than deaths, and this can be referred to natural increase, thus leading to population increase. Immigration has contributed to population, in developed countries. As people from developing countries move to these countries to seek better prospects.

Hope this helps and hope this is what you are looking for!

you should think about the answers you give and expect the same form your questions.

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.