Vascular cambium forms one of the following on its inner side.
A.Bast fibres – produced from the vascular cambium towards outerside
B.Sieve tubes – produced from procambium towards outerside.
C.Wood fibres – produced from the vascular cambium towards innerside.
D.Companion cell – produced from procambium towards outerside.
So, the correct option is ‘Wood fibres’.