The correct option is B Dorsal part of diencephalon
The diencephalon is the region of the embryonic vertebrate neural tube that gives rise to posterior forebrain structures including the thalamus, hypothalamus, posterior portion of the pituitary gland, and pineal gland. The pineal gland arises as a dorsal outgrowth of the caudal portion of the diencephalon. In the adult animal, it lies in the midline of the roof of the third ventricle.