Which of the following is the best example of the use of substantive expertise in the "Prepare the Data" step of the data science framework?

A$)$ knowing how the statistical concepts of mean, mode, and median help explain the data

B$)$ understanding how variance and standard deviation are calculated

C$)$ referring to the data dictionary of the data base to understand the concept of annual income and to see if it aligns well with U$.$S$.$ GAAP

D$)$ understanding the dataset structure of a general ledger database