Concept :Modified stem :The stem is the central axis that provides support to all the aerial parts of the plant.In some plants, these also help in perennation, vegetative propagation, food storage, and photosynthesis through various modifications.Their morphology and structure have been modified to suit the function they perform.Stem modifications can be seen in potato, ginger, garlic, yam, etc.Explanation :Potato :Stems get modified into underground structures for storage of food as seen in potato (tuber)Other examples are Ginger (rhizome), garlic (bulb), and yam (corm).The presence of an eye (node) in potato, distinct nodes with internodes and scaly leaves in ginger/yam, and a cluster of roots at the base of the reduced stem in garlic/ onion, all indicate that these underground plant parts are modified stem.Carrot :The carrot is an example of a modified root.It stores food and water.Radish :It is a modified tap root.It stores food and it becomes fusiform by swollen in the middle and gradually tapers towards the two ends.?Sweet potato :Sweet potato is a modified adventitious root.It stores food.?So, the correct answer is Potato.Radish Root?Sweet Potato: RootTaoica: RootPotato: StemAdditional InformationStems are also modified into runner (Cynodon dactylon, Oxalis)Runners are slender prostrate branches arising from axillary budsStolon (e.g., mint, strawberry) which is a slender lateral branch.