The correct option is C Cambium
Secondary growth refers to the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips of stems and roots, causing them to elongate and gives rise to primary tissue.
In many vascular plants, secondary growth is the result of the activity of the two lateral meristems, the cork cambium and vascular cambium. Arising from lateral meristems, secondary growth increases the girth of the plant root or stem, rather than its length. As long as the lateral meristems continue to produce new cells, the stem or root will continue to grow in diameter.
In woody plants, this process produces wood, and shapes the plant into a tree with a thickened trunk. So, active divisions occurs in cambium. Active divisions will not occurs in xylem, phloem and collenchyma.
Thus, the correct answer is option C.