Tables can not only contain metrics, but can also contain editable dropdowns when viewed in table mode.
To create a new dropdown
Navigate to your board and bring it into edit mode
Find the table you'd like to add a dropdown to and click the edit button to display its table options.
Scroll down the table options until you see "+Add Drop Down" in blue linked text. Select this option.
Now you should see a pop out modal that says "Add Option." Select this and enter your first option name.
These options are what will later be available when you select the dropdown.
Each option can be color-coded and named.
After giving the first option a name, select "choose color" and pick an associated color from the menu above. After selecting the color you should see it reflecting underneath the option.
Repeat this process until all options have been created.
After clicking "Save" you should now see an untitled drop down added to your table.
Give your dropdown a row title, then select the drop down to change its options. These options should be the same you just assigned when creating the drop down.
Copying drop downs
In most cases you want to use the same drop down options for multiple rows. To copy what you have created in one row, down to the next, select the copy icon below the drop down from the table options window.
Each time you select the copy icon you will see an untitled row with those same options appear at the bottom of the table.