Detailed Instructions: In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D". 
Q: [header] How to calculate difference in pivot table [title] Launch microsoft excel. [title] Open the spreadsheet containing the pivot table and source data you are working with. [title] Select the worksheet tab containing the source data. <sep> (A) [step] This is the area at the top of the page that displays as column c under excel. [title] Select new column size from the column tool bar located at the top. (B) [substeps] This may, or may not, be the same sheet where your pivot table is located. [title] Determine the calculation you would like to add. (C) [title] Enter the data to the new excel data page. [title] Click " analyze " into the " view sources " dialog box that's pop-up. (D) [step] Excel will automatically display the field for all calculations you've done here. [substeps] If there is more than one source, either double-click on the mass area to extract all of the formulas, or click the add or remove button on excel to root it.
A:
B