The correct answer is (b). Ginger is a rhizome, which is a modified underground stem. It is a horizontal, fleshy stem that grows horizontally along the ground. Rhizomes are often used for propagation, as they can be easily divided into smaller pieces and each piece will grow into a new plant. Ginger rhizomes are also used as a spice and in traditional medicine.
A bulb is a short, vertical stem that is surrounded by fleshy leaves. The leaves store food, which the plant uses to grow new leaves and flowers. Examples of bulbs include onions, garlic, and tulips.
A tuber is a swollen underground stem that stores food. Tubers are often used for propagation, as they can be easily divided into smaller pieces and each piece will grow into a new plant. Examples of tubers include potatoes, yams, and sweet potatoes.
A modified root is a root that has changed its shape or function to perform a different task. Examples of modified roots include carrots, turnips, and beets.