Concept:The oily substance that lubricates hair is sebum, produced by sebaceous glands.
Explanation:Sebaceous glands are associated with hair follicles in mammalian skin.
They secrete an oily substance called sebum.
Sebum keeps the hair flexible, soft, and water-repellent.
It also helps reduce friction and protects the skin from moisture loss.
Sweat glands produce sweat, not oil, so option A is incorrect.
Fatty cells store fat, and the granular layer is part of the epidermis; neither secretes this oily lubricant.
Therefore, the correct option is the one naming sebaceous glands.
Answer:B. sebaceous glands