Concept:The plant organ shown is an onion bulb, which is a modified underground stem with fleshy leaves.Explanation:The longitudinal section shows a short, conical stem at the base.Around this stem are thick, fleshy scale leaves that store food.Roots arise from the lower part of the stem.This structure is characteristic of a bulb.It is not a stem tuber, stolon, or runner.Answer:B. bulb
