The correct option is B adventitious root
Root and stem are the plant parts that arise from radicle and plumule of the germinating seed. Root generally grows towards the soil and stem grows away from the ground. In some plants, roots or the stem may get variously modified to meet certain requirements.
Sweet potato is an example of modified root. The edible part of sweet potato is a modified adventitious root that stores food. Adventitious roots are the roots that grow from parts other than the radicle. Tap root is a direct elongation of the radicle. Rhizome is a modified stem which stores food.