Gre Big Book test 4 Section 4

image
Here I am confused between C and E, I find both the blanks fitting appropriately in both these options. What am I missing here?

Please share your logic/reasoning for each answer choice.

Scientists can establish studies/norms. seconds idea is contrasted with the first one (which says it is clear), so second blank is something like misunderstanding /confusion

Do “studies” describe the appropriate behaviour? The word “appropriate” suggests there has to be judgment, while studies are objective, right>?