The function of oligodendrocyte is -: (A) Myelinates the CNS, (B) Nutrition of nervous tissue, (C) Lining the cavities of the CVS, (D) Behave like macrophages
Answer is A. The principal function of oligodendrocytes is the production and maintenance of myelin in CNS - Robbins

Myelination in Central nervous system → Oligodendrocytes
Myelination in Peripheral nervous system → Schwann cells