Question

Question #5f600

Answer 1

The pericycle of the procambium.

Explanation:

https://www.britannica.com/science/procambium

Figure 1.6 (in the following reference link) shows the different phases of the formation of the first periderm, from the initiation of the phellogen to the resulting cork layer after some years of growth.

During the first year only a few layers of phellem cells are formed, and in the second year they still keep their radial flattened appearance. It is only in the subsequent years that the cork cells enlarge in the radial direction and attain the typical appearance of cork cells.
https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/cork-cambium

See also:
https://study.com/academy/lesson/cork-cambium-definition-lesson-quiz.html