Which pair of scientific fields would be most useful in investigating human
activities and their impact on the environment?

The correct answer is:   [a]:   the "stratosphere" .

Its not chemical its not radiation and its not convection because there is not movement of fluids so it is thermal conduction

Large asteroid and comet impacts. because they can have a huge impact on the environment, such as a loss of land, and crust on the earth with the big holes they produce. on the other hand, volcanic eruptions can also cause change within the environment by producing land, but im actually not quite sure which one would be a better answer, hopefully you read this and didnt just flat out choose the first sentence i have spoken! your welcome~