[topic moved to Adobe Reader for iOS forum]
Adobe Reader for iOS supports drop-down boxes. What happens when you select an item in a drop down list?
Could you post a screenshot?
For the particular form in question, it was authored (likely initially via some field recognition algorithm) with several instances of a dropdown and a text field overlayed over one another. Because the text field is before the dropdown in field/tab order, on tap, it is processed first by the Mobile Reader. That is why your experience when using the Mobile Reader is that of a text field.
The Desktop Reader processes fields in reverse field/tab order (z-order), so the experience that user will see is that of a dropdown.
Hope this helps,