In spreadsheet applications, a valid range address specifies a block of cells. It typically consists of two cell references (the top-left and bottom-right cells of the range) separated by a colon (:

In spreadsheet applications, a valid range address specifies a block of cells. It typically consists of two cell references (the top-left and bottom-right cells of the range) separated by a colon (:). A cell reference is composed of one or more column letters followed by one or more row numbers (e.g., A1, B23, AA100). Entire columns or rows can also be referenced.

Let's evaluate each option:

• A1:A2: This is a valid range. A1 is a cell reference (Column A, Row 1) and A2 is a cell reference (Column A, Row 2).
• C8:A9: This is a valid range. C8 is a cell reference (Column C, Row 8) and A9 is a cell reference (Column A, Row 9).
• AA3:BB5: This is a valid range. AA3 is a cell reference (Column AA, Row 3) and BB5 is a cell reference (Column BB, Row 5).
• 9F:9G: This is an invalid range. Cell references must have the column letter(s) before the row number(s) (e.g., F9, G9, not 9F, 9G).
• E:G: This is a valid range. It refers to all cells in columns E, F, and G.
• 16:18: This is a valid range. It refers to all cells in rows 16, 17, and 18.

The valid range addresses are:

• A1:A2
• C8:A9
• AA3:BB5
• E:G
• 16:18