The correct answer is From different social and ethnic backgrounds.
Explanation:
The purpose of science studies is to gain an understanding of specific phenomena and use this in the benefit of the world or humanity. Moreover, science is guided by objective methods and these are applied all around the world. This feature allows scientists from all kinds of social and ethnic backgrounds to study the same phenomena and obtain similar results, which is essential for the progress of scientific knowledge. This is exemplified by two different labs in two different countries studying drug absorption because the results of these two studies can be analyzed together to understand drug absorption.
In this context, one factor that contributes to the progress of scientific knowledge is the effort of scientists "from different social and ethnic backgrounds".
