The correct option is A A
Cork cambium and vascular cambium are responsible for the increase in girth of plants. Vascular cambium and cork cambium are lateral meristem. The meristematic tissue that is found in the plant's peripheral zone, both at the stem and at the roots, is known as the lateral meristem. The lateral meristem is responsible for the expansion of the plant's diameter or girth, this type of growth in plants is also known as secondary growth.