AMPforWP - Opt-in Forms 
Description
The GravityWP – List Dropdown Add-on for Gravity Forms gives functionality to add a Dropdown Select with choices to a column or multiple columns in a Gravity Forms List Field.
Features
Make Dropdown Select List Columns: Turn your List Field columns into dropdown select fields with predefined choices. Supports both single and multicolumn Lists.
Enhanced User interface option: As in the default Gravity Forms dropdown select fields you can apply the enhanced user interface.
Backwards compatible: Compatible with the discontinued Drop Down Options in List Field for Gravity Forms plugin, except for the ‘Enable add options’ feature, which allowed users to add undefined options.