Redwood adoption - when is it mandatory ?

Hi,

Can Oracle please confirm :

1) Does a move to 25C force the activation of the Redwood screens, or is it possible to remain with the Responsive screens ?

2) If the Redwood screens can remain inactive in 25C, can we be assured of non-regression of the existing Responsive screens and processes ?

3) From when does Redwood adoption become mandatory ?

Right now we only use the Recruitment module.

Thanks.