A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data
Just a guess based on no usable information — The Option+▼ combination opens a list of textual data which exists in the column. It does nothing if the column contains Values:
Data can be selected from the list for a new entry or to replace an existing entry.
If that doesn't provide the information you need please provide a reasonable explanation of what that need is.