______ enlarges the stem and root in diameter.

Correct option is C

The correct answer is: (C) Cambium

Explanation:

• Cambium is a lateral meristem responsible for secondary growth in plants.

• It increases the diameter of stems and roots by producing new xylem (wood) and phloem tissues.

• This growth leads to the thickening of plant organs over time.

Information Booster:

• Cambium exists as vascular cambium (between xylem and phloem) and cork cambium (produces bark).

• It is active in dicotyledonous plants but absent in most monocots.

• Vascular cambium gives rise to annual rings in woody plants.

• Secondary xylem adds to the wood, and secondary phloem forms part of the bark.

• The cambium is not responsible for vertical growth, only lateral thickening.