The correct option is B, SEED.
The seed is a reproductive part of the flowering plants. It has many functions, these include: protection of embryo from injury, production of food for the embryo, protection of embryo from dehydration, etc. The vascular system of the flowering plants makes it possible for the seed to provide the embryo with nourishment; the vascular system is responsible for movement of nutrients and water to all the other part of the plant.