This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
A child is diagnosed with osteosarcoma based on sunray appearance on X-ray. This is because of: 
Select and explain. 
A. Calcification along the periosteum, B. Calcification along the blood vessels, C. Periosteal reaction, D. Soft tissue invasion
C: Periosteal reaction
Answer: C: Periosteal reaction 
Explanation: Ans. c. Periosteal reaction