Answer:
The correct answer would be C) stem.
Modified stems are used as storage organs in potato plant. They are also termed as stem tubers.
They are formed from thickened stolons or rhizomes.
They help in perennation and provide nutrients and energy for regrowth during the following growing season.
The underground tuber survives the winter until spring and help in regeneration of new shoots.
The new shoot uses the food stored in the tuber to grow.