This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolic and endocrine disorders, Subject name: Orthopaedics
which of the following is Marble bone disease ? 
Select and explain. 
A. Osteoporosis, B. Paget's disease, C. Osteopetrosis, D. Osteogenesis imperfecta
C: Osteopetrosis
Answer: C: Osteopetrosis 
Explanation: *Osteopetrosis is also known as marble bone disease or Albers- Schonberg disease. *Paget's disease is known as Osteitis deformans. *Osteogenesis imperfecta is known as Brittle bone disease. *Osteoporosis is known as Fragile bone disease. Ref: Maheshwari 9th/e p.307