The correct answer is option 2: vegetative reproduction. Bulbils are small, bud-like structures that are capable of growing into new plants. They are produced by certain plants as a form of asexual reproduction. Asexual reproduction does not involve the fusion of gametes (sex cells) and instead produces offspring that are genetically identical to the parent plant. In the case of bulbils, they are formed on the parent plant and can be detached to grow into independent plants. This form of reproduction provides an advantage for plants to spread and colonize new areas. Options 1, 3, and 4 are not correct in this context. Sexual reproduction involves the fusion of sex cells, food storage is not a specific function of bulbils, and respiration refers to the process of obtaining energy from oxygen, which is not directly related to the formation of bulbils.