The growth of the stem increases due to activity of
Meristems occur parallel to the circumference of the stems are called Lateral meristems. These are found only in dicotyledons. In this cells divide periclinal. It takes part in secondary growth and produces secondary tissues.
Due to this activity, the volume or girth of stem increases.
Eg: Intra fascicular cambium, inter fascicular cambium and cork cambium.
So, the correct option is ‘Lateral meristem’.