In any spreadsheet, the address of the first cell is typically referred to as the "cell reference." The correct answer in this case is option 4, A1. This is because the column is represented by a letter and the row is represented by a number. In a spreadsheet grid, the first cell is located at the intersection of column A and row 1. Thus, it is denoted as A1. Option 1 (OA) and option 3 (AO) are not correct because the column letter comes before the row number. Option 2 (1A) is also incorrect because the row number should be placed after the column letter. Therefore, option 4, A1, is the correct answer for the address of the first cell in a spreadsheet.