What does the column selector look like?

The column selector in applications like Microsoft Excel or similar spreadsheet programs is visually represented by a thick down arrow. This design allows users to easily identify the tool used for selecting entire columns in a worksheet. When the user hovers over the column header, this thick down arrow appears, indicating that clicking it will select all cells within that column. This visual cue is intuitive and helps streamline the process of working with data by enabling quick and effective selection.

The other options do not accurately represent the function of the column selector; for instance, a thin line might not provide the same level of clarity, while a filled square typically denotes cell selection, and an equal sign is commonly associated with formulas or functions rather than selection tools.