I need help finding out what the answer is to this

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.

What does it mean to say that "service sector" jobs are predominant in europe's mixed economies today? a. that jobs where people work in factories predominate b. that jobs where people do something for others predominate c. that jobs where people work the land predominate d. that jobs in government predominate

What is “the compromise of 1850? ” *