What is the level of organization of an onion bulb?

The level of organization of an onion bulb is an organ. An organ is a group of different tissues that work together to perform a specific function. In the case of an onion bulb, it is an underground storage organ composed of layers of fleshy leaves that store nutrients and water for the growth of the plant. Therefore, an onion bulb is considered an organ because it is made up of different types of tissues (e.g., protective epidermal tissue, storage parenchyma tissue) that work together to carry out the specific function of storage.