The correct answer is C. the month group footer section.
The month group footer section is a section of a report that appears at the end of each group of data. In this case, the data is grouped by month. The month group footer section is a good place to calculate the total sales for each month.
The report footer section is a section of a report that appears at the end of the report. It is a good place to calculate the total sales for the entire report. However, in this case, we are only interested in calculating the total sales for each month. Therefore, the month group footer section is a better choice.
The page footer section is a section of a report that appears at the bottom of each page. It is a good place to calculate the total number of pages in the report. However, in this case, we are not interested in calculating the total number of pages in the report. Therefore, the page footer section is not a good choice.
The summary section is a section of a report that appears at the end of the report. It is a good place to calculate the total sales for the entire report, as well as other summary statistics, such as the average sales per month. However, in this case, we are only interested in calculating the total sales for each month. Therefore, the summary section is not a good choice.