This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Osteogenic Sarcoma, Subject name: Orthopaedics
Which of the following is bone forming malignant tumour? 
Select and explain. 
A. Osteoid osteoma, B. Osteosarcoma, C. Chondrosarcoma, D. Giant cell tumour
B: Osteosarcoma
Answer: B: Osteosarcoma 
Explanation: Ans. is 'b' i.e., Osteosarcoma o Bone-forming tumours are a sub-set of bone tumours that are characterised by their propensity to form excess osteoid. They can be further subdivided into benign and malignant tumours.Benign tumours# Osteoid osteoma# Osteoblastoma# Bone island (enostosis)# Osteopoikilosis# OsteomaMalignant tumourso Malignant bone-forming tumours are all osteosarcomas.# Osteosarcoma (conventional)# Telangiectatic osteosarcoma# Low-grade central osteosarcoma