If there are many individual differences that could confound your study, what is the best approach for creating equivalent groups in that case

As our current atmosphere formed, the concentrations of various atmospheric gases fluctuated. match each gas with the explanation that best describes how its proportion changed during the evolution of the atmosphere.

Which example define natural rights ?

Does (flavius) josephus believe the romans were merciful when they conquered people? how does he try to persuade the reader to support his belief?