The correct option is C Canaliculi
Osteocytes are flattened cells with a central nucleus and numerous cytoplasmic processes. They occupy spaces in the matrix, called as lacunae. Canaliculi radiate from each lacuna and permit diffusion of nutritive material. Protoplasmic processes occupy the canaliculi. The osteocytes remain alive in the calcified matrix and secrete alkaline phosphatase to maintain calcification. Hence, option D is correct.