<h2>Ur Answer:-</h2>
The cambial ring becomes active and starts cutting off new cells; both on the inner and the outer sides. The cells which are cut off towards the pith mature into secondary xylem. The cells which are cut off towards the periphery mature into secondary phloem.
<h2>Hope it helps uh!</h2>
That would be A- Osmosis.
I hope this helps! (:
That is when extinction occurs. Hope I helped!