What is Funneling?
Funneling takes a form user's selected choices from a previous multiple choice item and sends — or "funnels" — them into the choices of a future multiple choice item.
Funneling requires a source multiple choice item and a destination multiple choice item, with the source item on a page before the destination item. You can split your form into multiple pages by adding Page Break items. It's best to make the source item a required item to ensure there will always be at least one choice to send to the destination item. If the destination item doesn't receive any choices it won't work.
Create the source item first. Then, create the destination item and for its choices choose the "Funnel Choices" option. If needed, you can "chain" together more than two items by Funneling from a first item to a second item and then from that second item to a third item, etc.
Any multiple choice item type (Checkbox, Radio Button, Dropdown, etc.) can be used as a source item or a destination item. Matrix, Ranking, and Rating items can additionally be used as destination items.
After two items are linked with Funneling, to keep the two items in sync, the choices for the source item can't be changed anymore without first disabling the Funneling. After your form has collected results, the Funneling settings can't be changed at all anymore to protect the stored results.