Answer: Limitation: They may be more expensive and time consuming than lab experiments. Limitation: There is no control over extraneous variables that might bias the results. This makes it difficult for another researcher to replicate the study in exactly the same way.
Explanation:
Hope this helps!
I would go with C, because you would always start with products and end with reactants.
3 is C i believe, and as for 4 minerals are solid, natural.. that's about all I can say...
