To create a drop-down list, select cell where you want it to be (in this case, cell I2), and in the Data tab on the ribbon, click "Data Validation" in the drop-down option with the same name.

Learn how to ensure accurate data entry in Excel by creating drop-down lists for consistency in your spreadsheets with the help of this guide ...

Learn to create efficient, interconnected Excel drop-down lists using range functions and data validation techniques. Multi-level drop-down ...