The correct option is D Stem
The portion of the stem that is underground, the modified stem which serves two functions such as storage of food and germination with help of axillary bud in suitable condition. These are called as tubers. In tubers, the stem is swollen and the nodal regions are called the eyes. Each eye has scaly leaves and axillary buds which develop into new plants when the tuber is planted e.g., potato. In sugar cane also, the nodes of stem give rise to the new plant. Thus, option C is correct.