Answer:
Option C, Qualitative
Step-by-step explanation:
A qualitative data set consists of description of processes. These process may include measures to do something, ways to conduct some task or even impact of several factors on something.
Here, in this case scientist is dealing with a data set that talks about methods/ways/techniques to grow corns in different soil which is purely a subjective data base consisting of procedures defining the cultivation of corn in different soil types. Hence option C is the correct answer.