<prompt> The Radiological hallmark of Osteo SA-Soap bubble appearanceSun ray appearanceOsteoid formation by neoplastic cellsCotton wool appearance  <response>: Ans. is b i.e. sunray appearance .X-ray features of Osteosarcoma.Area of irregular destruction of metaphysesErosion of the overlying cortex.New bone formation in the matrix of the tumorPeriosteal reaction which is irregular; periosteal reaction in osteomyelitis is smoothCodmans triangleSun-ray appearance 