Looking Out Your Window, You May Notice That the Bark

Looking out your window, you may notice that the bark of a nearby oak tree has a mosaic appearance, consisting of deep fissures and relatively flat areas. What accounts for this mosaic appearance?

A) the formation of new cork cambia as old cork cambia grow away from the phloem
B) the formation of new secondary phloem in distinct, discontinuous patches
C) the formation of new cork cambia in distinct, discontinuous patches
D) the formation of new vascular cambia as old cork cambia grow away from the phloem