The correct option is D All of the above
The harderian gland is a gland found within the eye's orbit, which occurs in tetrapods (reptiles, amphibians, birds and mammals) that possess a nictitating membrane. The gland can be compound tubular or compound tubuloalveolar, and the fluid it secretes (mucous, serous or lipid) varies between different groups of animals. In some animals it acts as an accessory to the lacrimal gland, secreting fluid that eases movement of the nictitating membrane.