The Autosum feature:

The Autosum feature, a staple in spreadsheet applications like Microsoft Excel, is specifically engineered to streamline the process of aggregating numerical data. Its core functionality is to automatically detect and sum a contiguous range of cells, typically those immediately above or to the left of the active cell, by inserting the appropriate SUM function. This capability dramatically reduces the need for manual formula entry, thereby saving time and minimizing the risk of calculation errors. While other spreadsheet features exist, option A, "Extends a sequential series of data," describes the Fill Handle's function, which is for pattern recognition and data extension. Option C, "Applies a border around the selected cells," relates to cell formatting, not calculation. Thus, Autosum's distinct purpose is to efficiently sum a range of cell values, making it a powerful tool for quick data analysis.