This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skeletal system, Subject name: Radiology
Which is the earliest radiologic feature of bone infection 
Select and explain. 
A. Destructive lytic lesion, B. Presence of periosteal reaction, C. Soft tissue edema, D. Appearance of sequestra
C: Soft tissue edema
Answer: C: Soft tissue edema 
Explanation: Sequence of changes in bone infection (osteomyelitis) on X-ray are : Earliest finding of osteomyelitis on X ray within 8 days is soft tisse swelling and loss of soft tissue planes Bone destruction and formation of periosteal reaction seen at 10-14 days Invoucrum formation at 3 weeks Sequestrum formation at 4 weeks